2018-11-29 18:49:38

by Qian Cai

[permalink] [raw]
Subject: [PATCH] efi: let kmemleak ignore false positives

unreferenced object 0xffff8096c1acf580 (size 128):
comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
hex dump (first 32 bytes):
80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00 ................
00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b ........kkkkkkkk
backtrace:
[<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
[<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
[<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
[<00000000edf04e07>] its_cpu_init+0x104/0x150
[<000000004d0342c5>] gic_starting_cpu+0x34/0x40
[<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
[<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
[<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
[<0000000015137d6a>] 0xffffffffffffffff

efi_mem_reserve_persistent+0x50/0xf8:
kmalloc at include/linux/slab.h:546
(inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979

This line,

rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);

Kmemleak has a known limitation that can only track pointers in the kernel
virtual space. Hence, it will report false positives due to "rsv" will only
reference to other physical addresses,

rsv->next = efi_memreserve_root->next;
efi_memreserve_root->next = __pa(rsv);

Signed-off-by: Qian Cai <[email protected]>
---
drivers/firmware/efi/efi.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index fad7c62..0b69bb6 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -31,6 +31,7 @@
#include <linux/acpi.h>
#include <linux/ucs2_string.h>
#include <linux/memblock.h>
+#include <linux/kmemleak.h>

#include <asm/early_ioremap.h>

@@ -980,6 +981,8 @@ int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
if (!rsv)
return -ENOMEM;

+ kmemleak_ignore(rsv);
+
rsv->base = addr;
rsv->size = size;

--
1.8.3.1



2018-12-06 16:18:41

by Qian Cai

[permalink] [raw]
Subject: [RESEND PATCH] efi: let kmemleak ignore false positives

unreferenced object 0xffff8096c1acf580 (size 128):
comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
hex dump (first 32 bytes):
80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00 ................
00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b ........kkkkkkkk
backtrace:
[<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
[<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
[<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
[<00000000edf04e07>] its_cpu_init+0x104/0x150
[<000000004d0342c5>] gic_starting_cpu+0x34/0x40
[<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
[<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
[<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
[<0000000015137d6a>] 0xffffffffffffffff

efi_mem_reserve_persistent+0x50/0xf8:
kmalloc at include/linux/slab.h:546
(inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979

This line,

rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);

Kmemleak has a known limitation that can only track pointers in the kernel
virtual space. Hence, it will report false positives due to "rsv" will only
reference to other physical addresses,

rsv->next = efi_memreserve_root->next;
efi_memreserve_root->next = __pa(rsv);

Signed-off-by: Qian Cai <[email protected]>
---
drivers/firmware/efi/efi.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 415849bab233..7fcfe8a7ae98 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -31,6 +31,7 @@
#include <linux/acpi.h>
#include <linux/ucs2_string.h>
#include <linux/memblock.h>
+#include <linux/kmemleak.h>

#include <asm/early_ioremap.h>

@@ -1000,6 +1001,8 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
if (!rsv)
return -ENOMEM;

+ kmemleak_ignore(rsv);
+
rsv->base = addr;
rsv->size = size;

--
2.17.2 (Apple Git-113)


2018-12-06 18:01:37

by Catalin Marinas

[permalink] [raw]
Subject: Re: [RESEND PATCH] efi: let kmemleak ignore false positives

On Thu, Dec 06, 2018 at 11:16:33AM -0500, Qian Cai wrote:
> unreferenced object 0xffff8096c1acf580 (size 128):
> comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
> hex dump (first 32 bytes):
> 80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00 ................
> 00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b ........kkkkkkkk
> backtrace:
> [<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
> [<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
> [<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
> [<00000000edf04e07>] its_cpu_init+0x104/0x150
> [<000000004d0342c5>] gic_starting_cpu+0x34/0x40
> [<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
> [<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
> [<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
> [<0000000015137d6a>] 0xffffffffffffffff
>
> efi_mem_reserve_persistent+0x50/0xf8:
> kmalloc at include/linux/slab.h:546
> (inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979
>
> This line,
>
> rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
>
> Kmemleak has a known limitation that can only track pointers in the kernel
> virtual space. Hence, it will report false positives due to "rsv" will only
> reference to other physical addresses,
>
> rsv->next = efi_memreserve_root->next;
> efi_memreserve_root->next = __pa(rsv);
>
> Signed-off-by: Qian Cai <[email protected]>

Acked-by: Catalin Marinas <[email protected]>

2018-12-06 18:03:07

by Ard Biesheuvel

[permalink] [raw]
Subject: Re: [RESEND PATCH] efi: let kmemleak ignore false positives

On Thu, 6 Dec 2018 at 19:00, Catalin Marinas <[email protected]> wrote:
>
> On Thu, Dec 06, 2018 at 11:16:33AM -0500, Qian Cai wrote:
> > unreferenced object 0xffff8096c1acf580 (size 128):
> > comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
> > hex dump (first 32 bytes):
> > 80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00 ................
> > 00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b ........kkkkkkkk
> > backtrace:
> > [<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
> > [<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
> > [<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
> > [<00000000edf04e07>] its_cpu_init+0x104/0x150
> > [<000000004d0342c5>] gic_starting_cpu+0x34/0x40
> > [<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
> > [<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
> > [<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
> > [<0000000015137d6a>] 0xffffffffffffffff
> >
> > efi_mem_reserve_persistent+0x50/0xf8:
> > kmalloc at include/linux/slab.h:546
> > (inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979
> >
> > This line,
> >
> > rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
> >
> > Kmemleak has a known limitation that can only track pointers in the kernel
> > virtual space. Hence, it will report false positives due to "rsv" will only
> > reference to other physical addresses,
> >
> > rsv->next = efi_memreserve_root->next;
> > efi_memreserve_root->next = __pa(rsv);
> >
> > Signed-off-by: Qian Cai <[email protected]>
>
> Acked-by: Catalin Marinas <[email protected]>\

I don't see the patch and I wasn't cc'ed

2018-12-06 18:06:34

by Qian Cai

[permalink] [raw]
Subject: Re: [RESEND PATCH] efi: let kmemleak ignore false positives

On Thu, 2018-12-06 at 19:01 +0100, Ard Biesheuvel wrote:
> On Thu, 6 Dec 2018 at 19:00, Catalin Marinas <[email protected]> wrote:
> >
> > On Thu, Dec 06, 2018 at 11:16:33AM -0500, Qian Cai wrote:
> > > unreferenced object 0xffff8096c1acf580 (size 128):
> > >   comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
> > >   hex dump (first 32 bytes):
> > >     80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00  ................
> > >     00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b  ........kkkkkkkk
> > >   backtrace:
> > >     [<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
> > >     [<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
> > >     [<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
> > >     [<00000000edf04e07>] its_cpu_init+0x104/0x150
> > >     [<000000004d0342c5>] gic_starting_cpu+0x34/0x40
> > >     [<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
> > >     [<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
> > >     [<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
> > >     [<0000000015137d6a>] 0xffffffffffffffff
> > >
> > > efi_mem_reserve_persistent+0x50/0xf8:
> > > kmalloc at include/linux/slab.h:546
> > > (inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979
> > >
> > > This line,
> > >
> > > rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
> > >
> > > Kmemleak has a known limitation that can only track pointers in the kernel
> > > virtual space. Hence, it will report false positives due to "rsv" will
> > > only
> > > reference to other physical addresses,
> > >
> > > rsv->next = efi_memreserve_root->next;
> > > efi_memreserve_root->next = __pa(rsv);
> > >
> > > Signed-off-by: Qian Cai <[email protected]>
> >
> > Acked-by: Catalin Marinas <[email protected]>\
>
> I don't see the patch and I wasn't cc'ed

That is strange. Please see,

https://lore.kernel.org/lkml/[email protected]/

2018-12-07 11:30:00

by Ard Biesheuvel

[permalink] [raw]
Subject: Re: [RESEND PATCH] efi: let kmemleak ignore false positives

On Thu, 6 Dec 2018 at 19:05, Qian Cai <[email protected]> wrote:
>
> On Thu, 2018-12-06 at 19:01 +0100, Ard Biesheuvel wrote:
> > On Thu, 6 Dec 2018 at 19:00, Catalin Marinas <[email protected]> wrote:
> > >
> > > On Thu, Dec 06, 2018 at 11:16:33AM -0500, Qian Cai wrote:
> > > > unreferenced object 0xffff8096c1acf580 (size 128):
> > > > comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
> > > > hex dump (first 32 bytes):
> > > > 80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00 ................
> > > > 00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b ........kkkkkkkk
> > > > backtrace:
> > > > [<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
> > > > [<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
> > > > [<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
> > > > [<00000000edf04e07>] its_cpu_init+0x104/0x150
> > > > [<000000004d0342c5>] gic_starting_cpu+0x34/0x40
> > > > [<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
> > > > [<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
> > > > [<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
> > > > [<0000000015137d6a>] 0xffffffffffffffff
> > > >
> > > > efi_mem_reserve_persistent+0x50/0xf8:
> > > > kmalloc at include/linux/slab.h:546
> > > > (inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979
> > > >
> > > > This line,
> > > >
> > > > rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
> > > >
> > > > Kmemleak has a known limitation that can only track pointers in the kernel
> > > > virtual space. Hence, it will report false positives due to "rsv" will
> > > > only
> > > > reference to other physical addresses,
> > > >
> > > > rsv->next = efi_memreserve_root->next;
> > > > efi_memreserve_root->next = __pa(rsv);
> > > >
> > > > Signed-off-by: Qian Cai <[email protected]>
> > >
> > > Acked-by: Catalin Marinas <[email protected]>\
> >
> > I don't see the patch and I wasn't cc'ed
>
> That is strange. Please see,
>
> https://lore.kernel.org/lkml/[email protected]/

OK, I found it in my spam folder, apologies for that.

This kmalloc() will be replaced in the next merge window by a call to
__get_free_page(). Does kmemleak still require the kmemleak_ignore()
for that case? Or is it only for kmalloc()?

2018-12-07 12:34:56

by Qian Cai

[permalink] [raw]
Subject: Re: [RESEND PATCH] efi: let kmemleak ignore false positives


On 12/7/18 at 6:28 AM, Ard Biesheuvel wrote:

> On Thu, 6 Dec 2018 at 19:05, Qian Cai <[email protected]> wrote:
> >
> > On Thu, 2018-12-06 at 19:01 +0100, Ard Biesheuvel wrote:
> > > On Thu, 6 Dec 2018 at 19:00, Catalin Marinas <[email protected]> wrote:
> > > >
> > > > On Thu, Dec 06, 2018 at 11:16:33AM -0500, Qian Cai wrote:
> > > > > unreferenced object 0xffff8096c1acf580 (size 128):
> > > > > comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
> > > > > hex dump (first 32 bytes):
> > > > > 80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00 ................
> > > > > 00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b ........kkkkkkkk
> > > > > backtrace:
> > > > > [<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
> > > > > [<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
> > > > > [<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
> > > > > [<00000000edf04e07>] its_cpu_init+0x104/0x150
> > > > > [<000000004d0342c5>] gic_starting_cpu+0x34/0x40
> > > > > [<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
> > > > > [<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
> > > > > [<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
> > > > > [<0000000015137d6a>] 0xffffffffffffffff
> > > > >
> > > > > efi_mem_reserve_persistent+0x50/0xf8:
> > > > > kmalloc at include/linux/slab.h:546
> > > > > (inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979
> > > > >
> > > > > This line,
> > > > >
> > > > > rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
> > > > >
> > > > > Kmemleak has a known limitation that can only track pointers in the kernel
> > > > > virtual space. Hence, it will report false positives due to "rsv" will
> > > > > only
> > > > > reference to other physical addresses,
> > > > >
> > > > > rsv->next = efi_memreserve_root->next;
> > > > > efi_memreserve_root->next = __pa(rsv);
> > > > >
> > > > > Signed-off-by: Qian Cai <[email protected]>
> > > >
> > > > Acked-by: Catalin Marinas <[email protected]>\
> > >
> > > I don't see the patch and I wasn't cc'ed
> >
> > That is strange. Please see,
> >
> > https://lore.kernel.org/lkml/[email protected]/
>
> OK, I found it in my spam folder, apologies for that.
>
> This kmalloc() will be replaced in the next merge window by a call to
> __get_free_page(). Does kmemleak still require the kmemleak_ignore()
> for that case? Or is it only for kmalloc()?

Looks like kmemleak won’t be able to track page
allocation, so it should be fine then without
kmemleak_ignore().

2018-12-07 12:46:37

by Ard Biesheuvel

[permalink] [raw]
Subject: Re: [RESEND PATCH] efi: let kmemleak ignore false positives

On Fri, 7 Dec 2018 at 13:32, Qian Cai <[email protected]> wrote:
>
>
> On 12/7/18 at 6:28 AM, Ard Biesheuvel wrote:
>
> > On Thu, 6 Dec 2018 at 19:05, Qian Cai <[email protected]> wrote:
> > >
> > > On Thu, 2018-12-06 at 19:01 +0100, Ard Biesheuvel wrote:
> > > > On Thu, 6 Dec 2018 at 19:00, Catalin Marinas <[email protected]> wrote:
> > > > >
> > > > > On Thu, Dec 06, 2018 at 11:16:33AM -0500, Qian Cai wrote:
> > > > > > unreferenced object 0xffff8096c1acf580 (size 128):
> > > > > > comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
> > > > > > hex dump (first 32 bytes):
> > > > > > 80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00 ................
> > > > > > 00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b ........kkkkkkkk
> > > > > > backtrace:
> > > > > > [<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
> > > > > > [<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
> > > > > > [<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
> > > > > > [<00000000edf04e07>] its_cpu_init+0x104/0x150
> > > > > > [<000000004d0342c5>] gic_starting_cpu+0x34/0x40
> > > > > > [<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
> > > > > > [<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
> > > > > > [<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
> > > > > > [<0000000015137d6a>] 0xffffffffffffffff
> > > > > >
> > > > > > efi_mem_reserve_persistent+0x50/0xf8:
> > > > > > kmalloc at include/linux/slab.h:546
> > > > > > (inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979
> > > > > >
> > > > > > This line,
> > > > > >
> > > > > > rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
> > > > > >
> > > > > > Kmemleak has a known limitation that can only track pointers in the kernel
> > > > > > virtual space. Hence, it will report false positives due to "rsv" will
> > > > > > only
> > > > > > reference to other physical addresses,
> > > > > >
> > > > > > rsv->next = efi_memreserve_root->next;
> > > > > > efi_memreserve_root->next = __pa(rsv);
> > > > > >
> > > > > > Signed-off-by: Qian Cai <[email protected]>
> > > > >
> > > > > Acked-by: Catalin Marinas <[email protected]>\
> > > >
> > > > I don't see the patch and I wasn't cc'ed
> > >
> > > That is strange. Please see,
> > >
> > > https://lore.kernel.org/lkml/[email protected]/
> >
> > OK, I found it in my spam folder, apologies for that.
> >
> > This kmalloc() will be replaced in the next merge window by a call to
> > __get_free_page(). Does kmemleak still require the kmemleak_ignore()
> > for that case? Or is it only for kmalloc()?
>
> Looks like kmemleak won’t be able to track page
> allocation, so it should be fine then without
> kmemleak_ignore().

OK, thanks Qian

I will take the patch for v4.20 and remove the kmemleak_ignore() again for v4.21