When loading a module with rodata=n, it causes an executing
NX-protected page BUG.
[ 32.379191] kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
[ 32.382917] BUG: unable to handle page fault for address: ffffffffc0005000
[ 32.385947] #PF: supervisor instruction fetch in kernel mode
[ 32.387662] #PF: error_code(0x0011) - permissions violation
[ 32.389352] PGD 240c067 P4D 240c067 PUD 240e067 PMD 421a52067 PTE 8000000421a53063
[ 32.391396] Oops: 0011 [#1] SMP PTI
[ 32.392478] CPU: 7 PID: 2697 Comm: insmod Tainted: G O 5.2.0-rc5+ #202
[ 32.394588] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
[ 32.398157] RIP: 0010:ko_test_init+0x0/0x1000 [ko_test]
[ 32.399662] Code: Bad RIP value.
[ 32.400621] RSP: 0018:ffffc900029f3ca8 EFLAGS: 00010246
[ 32.402171] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[ 32.404332] RDX: 00000000000004c7 RSI: 0000000000000cc0 RDI: ffffffffc0005000
[ 32.406347] RBP: ffffffffc0005000 R08: ffff88842fbebc40 R09: ffffffff810ede4a
[ 32.408392] R10: ffffea00108e3480 R11: 0000000000000000 R12: ffff88842bee21a0
[ 32.410472] R13: 0000000000000001 R14: 0000000000000001 R15: ffffc900029f3e78
[ 32.412609] FS: 00007fb4f0c0a700(0000) GS:ffff88842fbc0000(0000) knlGS:0000000000000000
[ 32.414722] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 32.416290] CR2: ffffffffc0004fd6 CR3: 0000000421a90004 CR4: 0000000000020ee0
[ 32.418471] Call Trace:
[ 32.419136] do_one_initcall+0x41/0x1df
[ 32.420199] ? _cond_resched+0x10/0x40
[ 32.421433] ? kmem_cache_alloc_trace+0x36/0x160
[ 32.422827] do_init_module+0x56/0x1f7
[ 32.423946] load_module+0x1e67/0x2580
[ 32.424947] ? __alloc_pages_nodemask+0x150/0x2c0
[ 32.426413] ? map_vm_area+0x2d/0x40
[ 32.427530] ? __vmalloc_node_range+0x1ef/0x260
[ 32.428850] ? __do_sys_init_module+0x135/0x170
[ 32.430060] ? _cond_resched+0x10/0x40
[ 32.431249] __do_sys_init_module+0x135/0x170
[ 32.432547] do_syscall_64+0x43/0x120
[ 32.433853] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Because if rodata=n, set_memory_x() cann't be called, fix this by
calling set_memory_x in complete_formation();
Fixes: f2c65fb3221a ("x86/modules: Avoid breaking W^X while loading modules")
Suggested-by: Jian Cheng <[email protected]>
Signed-off-by: Yang Yingliang <[email protected]>
---
kernel/module.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index 80c7c09584cf..1a5d879573c3 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1949,12 +1949,10 @@ void module_enable_ro(const struct module *mod, bool after_init)
set_vm_flush_reset_perms(mod->core_layout.base);
set_vm_flush_reset_perms(mod->init_layout.base);
frob_text(&mod->core_layout, set_memory_ro);
- frob_text(&mod->core_layout, set_memory_x);
frob_rodata(&mod->core_layout, set_memory_ro);
frob_text(&mod->init_layout, set_memory_ro);
- frob_text(&mod->init_layout, set_memory_x);
frob_rodata(&mod->init_layout, set_memory_ro);
@@ -2018,6 +2016,12 @@ void set_all_modules_text_ro(void)
static void module_enable_nx(const struct module *mod) { }
#endif
+static void module_enable_x(const struct module *mod)
+{
+ frob_text(&mod->core_layout, set_memory_x);
+ frob_text(&mod->init_layout, set_memory_x);
+}
+
#ifdef CONFIG_LIVEPATCH
/*
* Persist Elf information about a module. Copy the Elf header,
@@ -3616,6 +3620,7 @@ static int complete_formation(struct module *mod, struct load_info *info)
module_enable_ro(mod, false);
module_enable_nx(mod);
+ module_enable_x(mod);
/* Mark state as coming so strong_try_module_get() ignores us,
* but kallsyms etc. can see us. */
--
2.17.1
> On Jun 16, 2019, at 11:59 PM, Yang Yingliang <[email protected]> wrote:
>
> When loading a module with rodata=n, it causes an executing
> NX-protected page BUG.
>
> [ 32.379191] kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
> [ 32.382917] BUG: unable to handle page fault for address: ffffffffc0005000
> [ 32.385947] #PF: supervisor instruction fetch in kernel mode
> [ 32.387662] #PF: error_code(0x0011) - permissions violation
> [ 32.389352] PGD 240c067 P4D 240c067 PUD 240e067 PMD 421a52067 PTE 8000000421a53063
> [ 32.391396] Oops: 0011 [#1] SMP PTI
> [ 32.392478] CPU: 7 PID: 2697 Comm: insmod Tainted: G O 5.2.0-rc5+ #202
> [ 32.394588] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
> [ 32.398157] RIP: 0010:ko_test_init+0x0/0x1000 [ko_test]
> [ 32.399662] Code: Bad RIP value.
> [ 32.400621] RSP: 0018:ffffc900029f3ca8 EFLAGS: 00010246
> [ 32.402171] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> [ 32.404332] RDX: 00000000000004c7 RSI: 0000000000000cc0 RDI: ffffffffc0005000
> [ 32.406347] RBP: ffffffffc0005000 R08: ffff88842fbebc40 R09: ffffffff810ede4a
> [ 32.408392] R10: ffffea00108e3480 R11: 0000000000000000 R12: ffff88842bee21a0
> [ 32.410472] R13: 0000000000000001 R14: 0000000000000001 R15: ffffc900029f3e78
> [ 32.412609] FS: 00007fb4f0c0a700(0000) GS:ffff88842fbc0000(0000) knlGS:0000000000000000
> [ 32.414722] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 32.416290] CR2: ffffffffc0004fd6 CR3: 0000000421a90004 CR4: 0000000000020ee0
> [ 32.418471] Call Trace:
> [ 32.419136] do_one_initcall+0x41/0x1df
> [ 32.420199] ? _cond_resched+0x10/0x40
> [ 32.421433] ? kmem_cache_alloc_trace+0x36/0x160
> [ 32.422827] do_init_module+0x56/0x1f7
> [ 32.423946] load_module+0x1e67/0x2580
> [ 32.424947] ? __alloc_pages_nodemask+0x150/0x2c0
> [ 32.426413] ? map_vm_area+0x2d/0x40
> [ 32.427530] ? __vmalloc_node_range+0x1ef/0x260
> [ 32.428850] ? __do_sys_init_module+0x135/0x170
> [ 32.430060] ? _cond_resched+0x10/0x40
> [ 32.431249] __do_sys_init_module+0x135/0x170
> [ 32.432547] do_syscall_64+0x43/0x120
> [ 32.433853] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Because if rodata=n, set_memory_x() cann't be called, fix this by
> calling set_memory_x in complete_formation();
>
> Fixes: f2c65fb3221a ("x86/modules: Avoid breaking W^X while loading modules")
> Suggested-by: Jian Cheng <[email protected]>
> Signed-off-by: Yang Yingliang <[email protected]>
> ---
> kernel/module.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 80c7c09584cf..1a5d879573c3 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -1949,12 +1949,10 @@ void module_enable_ro(const struct module *mod, bool after_init)
> set_vm_flush_reset_perms(mod->core_layout.base);
> set_vm_flush_reset_perms(mod->init_layout.base);
> frob_text(&mod->core_layout, set_memory_ro);
> - frob_text(&mod->core_layout, set_memory_x);
>
> frob_rodata(&mod->core_layout, set_memory_ro);
>
> frob_text(&mod->init_layout, set_memory_ro);
> - frob_text(&mod->init_layout, set_memory_x);
>
> frob_rodata(&mod->init_layout, set_memory_ro);
>
> @@ -2018,6 +2016,12 @@ void set_all_modules_text_ro(void)
> static void module_enable_nx(const struct module *mod) { }
> #endif
>
> +static void module_enable_x(const struct module *mod)
> +{
> + frob_text(&mod->core_layout, set_memory_x);
> + frob_text(&mod->init_layout, set_memory_x);
> +}
> +
> #ifdef CONFIG_LIVEPATCH
> /*
> * Persist Elf information about a module. Copy the Elf header,
> @@ -3616,6 +3620,7 @@ static int complete_formation(struct module *mod, struct load_info *info)
>
> module_enable_ro(mod, false);
> module_enable_nx(mod);
> + module_enable_x(mod);
>
> /* Mark state as coming so strong_try_module_get() ignores us,
> * but kallsyms etc. can see us. */
> --
> 2.17.1
It does seem that I screwed up (thanks for fixing it!).
Makes me wonder why module_enable_ro() is needed to be called twice
(excluding the write-protecting of the core_layout). I wonder since this
patch would eliminate some calls to set_memory_x(), which indeed do not seem
necessary.
Skimming 444d13ff10fb1 ("modules: add ro_after_init support”), I could
not understand why.
Anyhow,
Reviewed-by: Nadav Amit <[email protected]>
+++ Yang Yingliang [17/06/19 14:59 +0800]:
>When loading a module with rodata=n, it causes an executing
>NX-protected page BUG.
>
>[ 32.379191] kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
>[ 32.382917] BUG: unable to handle page fault for address: ffffffffc0005000
>[ 32.385947] #PF: supervisor instruction fetch in kernel mode
>[ 32.387662] #PF: error_code(0x0011) - permissions violation
>[ 32.389352] PGD 240c067 P4D 240c067 PUD 240e067 PMD 421a52067 PTE 8000000421a53063
>[ 32.391396] Oops: 0011 [#1] SMP PTI
>[ 32.392478] CPU: 7 PID: 2697 Comm: insmod Tainted: G O 5.2.0-rc5+ #202
>[ 32.394588] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
>[ 32.398157] RIP: 0010:ko_test_init+0x0/0x1000 [ko_test]
>[ 32.399662] Code: Bad RIP value.
>[ 32.400621] RSP: 0018:ffffc900029f3ca8 EFLAGS: 00010246
>[ 32.402171] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
>[ 32.404332] RDX: 00000000000004c7 RSI: 0000000000000cc0 RDI: ffffffffc0005000
>[ 32.406347] RBP: ffffffffc0005000 R08: ffff88842fbebc40 R09: ffffffff810ede4a
>[ 32.408392] R10: ffffea00108e3480 R11: 0000000000000000 R12: ffff88842bee21a0
>[ 32.410472] R13: 0000000000000001 R14: 0000000000000001 R15: ffffc900029f3e78
>[ 32.412609] FS: 00007fb4f0c0a700(0000) GS:ffff88842fbc0000(0000) knlGS:0000000000000000
>[ 32.414722] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>[ 32.416290] CR2: ffffffffc0004fd6 CR3: 0000000421a90004 CR4: 0000000000020ee0
>[ 32.418471] Call Trace:
>[ 32.419136] do_one_initcall+0x41/0x1df
>[ 32.420199] ? _cond_resched+0x10/0x40
>[ 32.421433] ? kmem_cache_alloc_trace+0x36/0x160
>[ 32.422827] do_init_module+0x56/0x1f7
>[ 32.423946] load_module+0x1e67/0x2580
>[ 32.424947] ? __alloc_pages_nodemask+0x150/0x2c0
>[ 32.426413] ? map_vm_area+0x2d/0x40
>[ 32.427530] ? __vmalloc_node_range+0x1ef/0x260
>[ 32.428850] ? __do_sys_init_module+0x135/0x170
>[ 32.430060] ? _cond_resched+0x10/0x40
>[ 32.431249] __do_sys_init_module+0x135/0x170
>[ 32.432547] do_syscall_64+0x43/0x120
>[ 32.433853] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
>Because if rodata=n, set_memory_x() cann't be called, fix this by
>calling set_memory_x in complete_formation();
>
>Fixes: f2c65fb3221a ("x86/modules: Avoid breaking W^X while loading modules")
>Suggested-by: Jian Cheng <[email protected]>
>Signed-off-by: Yang Yingliang <[email protected]>
>---
> kernel/module.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
>diff --git a/kernel/module.c b/kernel/module.c
>index 80c7c09584cf..1a5d879573c3 100644
>--- a/kernel/module.c
>+++ b/kernel/module.c
>@@ -1949,12 +1949,10 @@ void module_enable_ro(const struct module *mod, bool after_init)
> set_vm_flush_reset_perms(mod->core_layout.base);
> set_vm_flush_reset_perms(mod->init_layout.base);
> frob_text(&mod->core_layout, set_memory_ro);
>- frob_text(&mod->core_layout, set_memory_x);
>
> frob_rodata(&mod->core_layout, set_memory_ro);
>
> frob_text(&mod->init_layout, set_memory_ro);
>- frob_text(&mod->init_layout, set_memory_x);
>
> frob_rodata(&mod->init_layout, set_memory_ro);
Just a style-related nit: could you also please shrink down this chunk
and remove the empty lines between the frob_* calls?
>@@ -2018,6 +2016,12 @@ void set_all_modules_text_ro(void)
> static void module_enable_nx(const struct module *mod) { }
> #endif
And note that we will need a stub for module_enable_x() here as well.
Thanks!
Jessica
+++ Nadav Amit [18/06/19 05:59 +0000]:
>> On Jun 16, 2019, at 11:59 PM, Yang Yingliang <[email protected]> wrote:
>>
>> When loading a module with rodata=n, it causes an executing
>> NX-protected page BUG.
>>
>> [ 32.379191] kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
>> [ 32.382917] BUG: unable to handle page fault for address: ffffffffc0005000
>> [ 32.385947] #PF: supervisor instruction fetch in kernel mode
>> [ 32.387662] #PF: error_code(0x0011) - permissions violation
>> [ 32.389352] PGD 240c067 P4D 240c067 PUD 240e067 PMD 421a52067 PTE 8000000421a53063
>> [ 32.391396] Oops: 0011 [#1] SMP PTI
>> [ 32.392478] CPU: 7 PID: 2697 Comm: insmod Tainted: G O 5.2.0-rc5+ #202
>> [ 32.394588] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
>> [ 32.398157] RIP: 0010:ko_test_init+0x0/0x1000 [ko_test]
>> [ 32.399662] Code: Bad RIP value.
>> [ 32.400621] RSP: 0018:ffffc900029f3ca8 EFLAGS: 00010246
>> [ 32.402171] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
>> [ 32.404332] RDX: 00000000000004c7 RSI: 0000000000000cc0 RDI: ffffffffc0005000
>> [ 32.406347] RBP: ffffffffc0005000 R08: ffff88842fbebc40 R09: ffffffff810ede4a
>> [ 32.408392] R10: ffffea00108e3480 R11: 0000000000000000 R12: ffff88842bee21a0
>> [ 32.410472] R13: 0000000000000001 R14: 0000000000000001 R15: ffffc900029f3e78
>> [ 32.412609] FS: 00007fb4f0c0a700(0000) GS:ffff88842fbc0000(0000) knlGS:0000000000000000
>> [ 32.414722] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ 32.416290] CR2: ffffffffc0004fd6 CR3: 0000000421a90004 CR4: 0000000000020ee0
>> [ 32.418471] Call Trace:
>> [ 32.419136] do_one_initcall+0x41/0x1df
>> [ 32.420199] ? _cond_resched+0x10/0x40
>> [ 32.421433] ? kmem_cache_alloc_trace+0x36/0x160
>> [ 32.422827] do_init_module+0x56/0x1f7
>> [ 32.423946] load_module+0x1e67/0x2580
>> [ 32.424947] ? __alloc_pages_nodemask+0x150/0x2c0
>> [ 32.426413] ? map_vm_area+0x2d/0x40
>> [ 32.427530] ? __vmalloc_node_range+0x1ef/0x260
>> [ 32.428850] ? __do_sys_init_module+0x135/0x170
>> [ 32.430060] ? _cond_resched+0x10/0x40
>> [ 32.431249] __do_sys_init_module+0x135/0x170
>> [ 32.432547] do_syscall_64+0x43/0x120
>> [ 32.433853] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Because if rodata=n, set_memory_x() cann't be called, fix this by
>> calling set_memory_x in complete_formation();
>>
>> Fixes: f2c65fb3221a ("x86/modules: Avoid breaking W^X while loading modules")
>> Suggested-by: Jian Cheng <[email protected]>
>> Signed-off-by: Yang Yingliang <[email protected]>
>> ---
>> kernel/module.c | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/module.c b/kernel/module.c
>> index 80c7c09584cf..1a5d879573c3 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -1949,12 +1949,10 @@ void module_enable_ro(const struct module *mod, bool after_init)
>> set_vm_flush_reset_perms(mod->core_layout.base);
>> set_vm_flush_reset_perms(mod->init_layout.base);
>> frob_text(&mod->core_layout, set_memory_ro);
>> - frob_text(&mod->core_layout, set_memory_x);
>>
>> frob_rodata(&mod->core_layout, set_memory_ro);
>>
>> frob_text(&mod->init_layout, set_memory_ro);
>> - frob_text(&mod->init_layout, set_memory_x);
>>
>> frob_rodata(&mod->init_layout, set_memory_ro);
>>
>> @@ -2018,6 +2016,12 @@ void set_all_modules_text_ro(void)
>> static void module_enable_nx(const struct module *mod) { }
>> #endif
>>
>> +static void module_enable_x(const struct module *mod)
>> +{
>> + frob_text(&mod->core_layout, set_memory_x);
>> + frob_text(&mod->init_layout, set_memory_x);
>> +}
>> +
>> #ifdef CONFIG_LIVEPATCH
>> /*
>> * Persist Elf information about a module. Copy the Elf header,
>> @@ -3616,6 +3620,7 @@ static int complete_formation(struct module *mod, struct load_info *info)
>>
>> module_enable_ro(mod, false);
>> module_enable_nx(mod);
>> + module_enable_x(mod);
>>
>> /* Mark state as coming so strong_try_module_get() ignores us,
>> * but kallsyms etc. can see us. */
>> --
>> 2.17.1
>
>It does seem that I screwed up (thanks for fixing it!).
>
>Makes me wonder why module_enable_ro() is needed to be called twice
>(excluding the write-protecting of the core_layout). I wonder since this
>patch would eliminate some calls to set_memory_x(), which indeed do not seem
>necessary.
>
>Skimming 444d13ff10fb1 ("modules: add ro_after_init support”), I could
>not understand why.
>
>Anyhow,
>
>Reviewed-by: Nadav Amit <[email protected]>
Indeed, you're right that the second module_enable_ro() call is mostly
redundant. It is for adding RO protection to the ro_after_init
section, but I believe the reason for redundancy was that we wanted to
re-use the function for livepatching, as livepatch calls
module_disable_ro() and module_enable_ro() to apply relocations.
Since module_enable_ro() was being called outside of the module
loader, we needed to make sure all RO protections were applied again,
including the ro_after_init section. I'll have to think about this
more to see if we can remove the redundancy without making the
module_enable_ro()/module_disable_ro() api too messy..
Thanks,
Jessica
On 2019/6/18 21:48, Jessica Yu wrote:
> +++ Yang Yingliang [17/06/19 14:59 +0800]:
>> When loading a module with rodata=n, it causes an executing
>> NX-protected page BUG.
>>
>> [ 32.379191] kernel tried to execute NX-protected page - exploit
>> attempt? (uid: 0)
>> [ 32.382917] BUG: unable to handle page fault for address:
>> ffffffffc0005000
>> [ 32.385947] #PF: supervisor instruction fetch in kernel mode
>> [ 32.387662] #PF: error_code(0x0011) - permissions violation
>> [ 32.389352] PGD 240c067 P4D 240c067 PUD 240e067 PMD 421a52067 PTE
>> 8000000421a53063
>> [ 32.391396] Oops: 0011 [#1] SMP PTI
>> [ 32.392478] CPU: 7 PID: 2697 Comm: insmod Tainted: G
>> O 5.2.0-rc5+ #202
>> [ 32.394588] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
>> BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
>> [ 32.398157] RIP: 0010:ko_test_init+0x0/0x1000 [ko_test]
>> [ 32.399662] Code: Bad RIP value.
>> [ 32.400621] RSP: 0018:ffffc900029f3ca8 EFLAGS: 00010246
>> [ 32.402171] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
>> 0000000000000000
>> [ 32.404332] RDX: 00000000000004c7 RSI: 0000000000000cc0 RDI:
>> ffffffffc0005000
>> [ 32.406347] RBP: ffffffffc0005000 R08: ffff88842fbebc40 R09:
>> ffffffff810ede4a
>> [ 32.408392] R10: ffffea00108e3480 R11: 0000000000000000 R12:
>> ffff88842bee21a0
>> [ 32.410472] R13: 0000000000000001 R14: 0000000000000001 R15:
>> ffffc900029f3e78
>> [ 32.412609] FS: 00007fb4f0c0a700(0000) GS:ffff88842fbc0000(0000)
>> knlGS:0000000000000000
>> [ 32.414722] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ 32.416290] CR2: ffffffffc0004fd6 CR3: 0000000421a90004 CR4:
>> 0000000000020ee0
>> [ 32.418471] Call Trace:
>> [ 32.419136] do_one_initcall+0x41/0x1df
>> [ 32.420199] ? _cond_resched+0x10/0x40
>> [ 32.421433] ? kmem_cache_alloc_trace+0x36/0x160
>> [ 32.422827] do_init_module+0x56/0x1f7
>> [ 32.423946] load_module+0x1e67/0x2580
>> [ 32.424947] ? __alloc_pages_nodemask+0x150/0x2c0
>> [ 32.426413] ? map_vm_area+0x2d/0x40
>> [ 32.427530] ? __vmalloc_node_range+0x1ef/0x260
>> [ 32.428850] ? __do_sys_init_module+0x135/0x170
>> [ 32.430060] ? _cond_resched+0x10/0x40
>> [ 32.431249] __do_sys_init_module+0x135/0x170
>> [ 32.432547] do_syscall_64+0x43/0x120
>> [ 32.433853] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Because if rodata=n, set_memory_x() cann't be called, fix this by
>> calling set_memory_x in complete_formation();
>>
>> Fixes: f2c65fb3221a ("x86/modules: Avoid breaking W^X while loading
>> modules")
>> Suggested-by: Jian Cheng <[email protected]>
>> Signed-off-by: Yang Yingliang <[email protected]>
>> ---
>> kernel/module.c | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/module.c b/kernel/module.c
>> index 80c7c09584cf..1a5d879573c3 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -1949,12 +1949,10 @@ void module_enable_ro(const struct module
>> *mod, bool after_init)
>> set_vm_flush_reset_perms(mod->core_layout.base);
>> set_vm_flush_reset_perms(mod->init_layout.base);
>> frob_text(&mod->core_layout, set_memory_ro);
>> - frob_text(&mod->core_layout, set_memory_x);
>>
>> frob_rodata(&mod->core_layout, set_memory_ro);
>>
>> frob_text(&mod->init_layout, set_memory_ro);
>> - frob_text(&mod->init_layout, set_memory_x);
>>
>> frob_rodata(&mod->init_layout, set_memory_ro);
>
> Just a style-related nit: could you also please shrink down this chunk
> and remove the empty lines between the frob_* calls?
OK，I will do it in next version.
>
>> @@ -2018,6 +2016,12 @@ void set_all_modules_text_ro(void)
>> static void module_enable_nx(const struct module *mod) { }
>> #endif
>
> And note that we will need a stub for module_enable_x() here as well.
module_enable_x() is outside of CONFIG_STRICT_MODULE_RWX.
>
> Thanks!
>
> Jessica
>
>
> .
>
+++ Yang Yingliang [19/06/19 10:28 +0800]:
>
>
>On 2019/6/18 21:48, Jessica Yu wrote:
>>+++ Yang Yingliang [17/06/19 14:59 +0800]:
>>>When loading a module with rodata=n, it causes an executing
>>>NX-protected page BUG.
>>>
>>>[ 32.379191] kernel tried to execute NX-protected page - exploit
>>>attempt? (uid: 0)
>>>[ 32.382917] BUG: unable to handle page fault for address:
>>>ffffffffc0005000
>>>[ 32.385947] #PF: supervisor instruction fetch in kernel mode
>>>[ 32.387662] #PF: error_code(0x0011) - permissions violation
>>>[ 32.389352] PGD 240c067 P4D 240c067 PUD 240e067 PMD 421a52067
>>>PTE 8000000421a53063
>>>[ 32.391396] Oops: 0011 [#1] SMP PTI
>>>[ 32.392478] CPU: 7 PID: 2697 Comm: insmod Tainted: G
>>>O 5.2.0-rc5+ #202
>>>[ 32.394588] Hardware name: QEMU Standard PC (i440FX + PIIX,
>>>1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org
>>>04/01/2014
>>>[ 32.398157] RIP: 0010:ko_test_init+0x0/0x1000 [ko_test]
>>>[ 32.399662] Code: Bad RIP value.
>>>[ 32.400621] RSP: 0018:ffffc900029f3ca8 EFLAGS: 00010246
>>>[ 32.402171] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
>>>0000000000000000
>>>[ 32.404332] RDX: 00000000000004c7 RSI: 0000000000000cc0 RDI:
>>>ffffffffc0005000
>>>[ 32.406347] RBP: ffffffffc0005000 R08: ffff88842fbebc40 R09:
>>>ffffffff810ede4a
>>>[ 32.408392] R10: ffffea00108e3480 R11: 0000000000000000 R12:
>>>ffff88842bee21a0
>>>[ 32.410472] R13: 0000000000000001 R14: 0000000000000001 R15:
>>>ffffc900029f3e78
>>>[ 32.412609] FS: 00007fb4f0c0a700(0000)
>>>GS:ffff88842fbc0000(0000) knlGS:0000000000000000
>>>[ 32.414722] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>[ 32.416290] CR2: ffffffffc0004fd6 CR3: 0000000421a90004 CR4:
>>>0000000000020ee0
>>>[ 32.418471] Call Trace:
>>>[ 32.419136] do_one_initcall+0x41/0x1df
>>>[ 32.420199] ? _cond_resched+0x10/0x40
>>>[ 32.421433] ? kmem_cache_alloc_trace+0x36/0x160
>>>[ 32.422827] do_init_module+0x56/0x1f7
>>>[ 32.423946] load_module+0x1e67/0x2580
>>>[ 32.424947] ? __alloc_pages_nodemask+0x150/0x2c0
>>>[ 32.426413] ? map_vm_area+0x2d/0x40
>>>[ 32.427530] ? __vmalloc_node_range+0x1ef/0x260
>>>[ 32.428850] ? __do_sys_init_module+0x135/0x170
>>>[ 32.430060] ? _cond_resched+0x10/0x40
>>>[ 32.431249] __do_sys_init_module+0x135/0x170
>>>[ 32.432547] do_syscall_64+0x43/0x120
>>>[ 32.433853] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>>
>>>Because if rodata=n, set_memory_x() cann't be called, fix this by
>>>calling set_memory_x in complete_formation();
>>>
>>>Fixes: f2c65fb3221a ("x86/modules: Avoid breaking W^X while
>>>loading modules")
>>>Suggested-by: Jian Cheng <[email protected]>
>>>Signed-off-by: Yang Yingliang <[email protected]>
>>>---
>>>kernel/module.c | 9 +++++++--
>>>1 file changed, 7 insertions(+), 2 deletions(-)
>>>
>>>diff --git a/kernel/module.c b/kernel/module.c
>>>index 80c7c09584cf..1a5d879573c3 100644
>>>--- a/kernel/module.c
>>>+++ b/kernel/module.c
>>>@@ -1949,12 +1949,10 @@ void module_enable_ro(const struct module
>>>*mod, bool after_init)
>>> set_vm_flush_reset_perms(mod->core_layout.base);
>>> set_vm_flush_reset_perms(mod->init_layout.base);
>>> frob_text(&mod->core_layout, set_memory_ro);
>>>- frob_text(&mod->core_layout, set_memory_x);
>>>
>>> frob_rodata(&mod->core_layout, set_memory_ro);
>>>
>>> frob_text(&mod->init_layout, set_memory_ro);
>>>- frob_text(&mod->init_layout, set_memory_x);
>>>
>>> frob_rodata(&mod->init_layout, set_memory_ro);
>>
>>Just a style-related nit: could you also please shrink down this chunk
>>and remove the empty lines between the frob_* calls?
>OK，I will do it in next version.
>
>>
>>>@@ -2018,6 +2016,12 @@ void set_all_modules_text_ro(void)
>>>static void module_enable_nx(const struct module *mod) { }
>>>#endif
>>
>>And note that we will need a stub for module_enable_x() here as well.
>module_enable_x() is outside of CONFIG_STRICT_MODULE_RWX.
Ah yeah you're right, my mistake. We need it outside of the
CONFIG_STRICT_MODULE_RWX block anyway since module_alloc() on x86
allocates memory with PAGE_KERNEL now instead of PAGE_KERNEL_EXEC and
we need to set text to executable regardless.