2009-03-25 00:16:18

by Ralf Baechle

Subject: [PATCH 2/2] MIPS: o32: Get rid of useless wrapper for llseek

Signed-off-by: Ralf Baechle <[email protected]>

arch/mips/kernel/linux32.c | 7 -------
arch/mips/kernel/scall64-o32.S | 2 +-
2 files changed, 1 insertions(+), 8 deletions(-)

diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
index 49aac6e..ab2da41 100644
--- a/arch/mips/kernel/linux32.c
+++ b/arch/mips/kernel/linux32.c
@@ -133,13 +133,6 @@ SYSCALL_DEFINE4(32_ftruncate64, unsigned long, fd, unsigned long, __dummy,
return sys_ftruncate(fd, merge_64(a2, a3));
}

-SYSCALL_DEFINE5(32_llseek, unsigned long, fd, unsigned long, offset_high,
- unsigned long, offset_low, loff_t __user *, result,
- unsigned long, origin)
-{
- return sys_llseek(fd, offset_high, offset_low, result, origin);
-}
-
/* From the Single Unix Spec: pread & pwrite act like lseek to pos + op +
lseek back to original location. They fail just like lseek does on
non-seekable files. */
diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
index b0fef4f..d928614 100644
--- a/arch/mips/kernel/scall64-o32.S
+++ b/arch/mips/kernel/scall64-o32.S
@@ -343,7 +343,7 @@ sys_call_table:
PTR sys_ni_syscall /* for afs_syscall */
PTR sys_setfsuid
PTR sys_setfsgid
- PTR sys_32_llseek /* 4140 */
+ PTR sys_llseek /* 4140 */
PTR compat_sys_getdents
PTR compat_sys_select
PTR sys_flock

2009-03-25 17:29:21

by Heiko Carstens

Subject: Re: [PATCH 2/2] MIPS: o32: Get rid of useless wrapper for llseek

On Wed, 25 Mar 2009 01:15:55 +0100
Ralf Baechle <[email protected]> wrote:

> Signed-off-by: Ralf Baechle <[email protected]>
>
> arch/mips/kernel/linux32.c | 7 -------
> arch/mips/kernel/scall64-o32.S | 2 +-
> 2 files changed, 1 insertions(+), 8 deletions(-)
>
> diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
> index 49aac6e..ab2da41 100644
> --- a/arch/mips/kernel/linux32.c
> +++ b/arch/mips/kernel/linux32.c
> @@ -133,13 +133,6 @@ SYSCALL_DEFINE4(32_ftruncate64, unsigned long, fd, unsigned long, __dummy,
> return sys_ftruncate(fd, merge_64(a2, a3));
> }
>
> -SYSCALL_DEFINE5(32_llseek, unsigned long, fd, unsigned long, offset_high,
> - unsigned long, offset_low, loff_t __user *, result,
> - unsigned long, origin)
> -{
> - return sys_llseek(fd, offset_high, offset_low, result, origin);
> -}
> -

Ah.. this hunk seems to be the origin of the bug. git commit
dbda6ac0897603f6c6dfadbbc37f9882177ec7ac "MIPS: CVE-2009-0029: Enable
syscall wrappers." contains this:

-asmlinkage int sys32_llseek(unsigned int fd, unsigned int offset_high,
- unsigned int offset_low, loff_t __user * result,
- unsigned int origin)
+SYSCALL_DEFINE5(32_llseek, unsigned long, fd, unsigned long, offset_high,
+ unsigned long, offset_low, loff_t __user *, result,
+ unsigned long, origin)

Here you converted offset_low from unsigned int to unsigned long. Hence
you lost the clearing of the upper 32 bits. That would explain the bug.
Any chance the process where the bug was seen was a compat process?

Patch below would probably fix it.

Btw. there are a lot of int->long conversions in the git commit
mentioned above. AFAICS all(?) of the conversions are wrong.

diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
index 1a86f84..5abcc7f 100644
--- a/arch/mips/kernel/linux32.c
+++ b/arch/mips/kernel/linux32.c
@@ -134,9 +134,9 @@ SYSCALL_DEFINE4(32_ftruncate64, unsigned long, fd, unsigned long, __dummy,
return sys_ftruncate(fd, merge_64(a2, a3));
}

-SYSCALL_DEFINE5(32_llseek, unsigned long, fd, unsigned long, offset_high,
- unsigned long, offset_low, loff_t __user *, result,
- unsigned long, origin)
+SYSCALL_DEFINE5(32_llseek, unsigned int, fd, unsigned int, offset_high,
+ unsigned int, offset_low, loff_t __user *, result,
+ unsigned int, origin)
{
return sys_llseek(fd, offset_high, offset_low, result, origin);
}

2009-03-25 19:28:57

by dann frazier

Subject: Re: [PATCH 2/2] MIPS: o32: Get rid of useless wrapper for llseek

On Wed, Mar 25, 2009 at 06:29:05PM +0100, Heiko Carstens wrote:
> On Wed, 25 Mar 2009 01:15:55 +0100
> Ralf Baechle <[email protected]> wrote:
>
> > Signed-off-by: Ralf Baechle <[email protected]>
> >
> > arch/mips/kernel/linux32.c | 7 -------
> > arch/mips/kernel/scall64-o32.S | 2 +-
> > 2 files changed, 1 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
> > index 49aac6e..ab2da41 100644
> > --- a/arch/mips/kernel/linux32.c
> > +++ b/arch/mips/kernel/linux32.c
> > @@ -133,13 +133,6 @@ SYSCALL_DEFINE4(32_ftruncate64, unsigned long, fd, unsigned long, __dummy,
> > return sys_ftruncate(fd, merge_64(a2, a3));
> > }
> >
> > -SYSCALL_DEFINE5(32_llseek, unsigned long, fd, unsigned long, offset_high,
> > - unsigned long, offset_low, loff_t __user *, result,
> > - unsigned long, origin)
> > -{
> > - return sys_llseek(fd, offset_high, offset_low, result, origin);
> > -}
> > -
>
> Ah.. this hunk seems to be the origin of the bug. git commit
> dbda6ac0897603f6c6dfadbbc37f9882177ec7ac "MIPS: CVE-2009-0029: Enable
> syscall wrappers." contains this:
>
> -asmlinkage int sys32_llseek(unsigned int fd, unsigned int offset_high,
> - unsigned int offset_low, loff_t __user * result,
> - unsigned int origin)
> +SYSCALL_DEFINE5(32_llseek, unsigned long, fd, unsigned long, offset_high,
> + unsigned long, offset_low, loff_t __user *, result,
> + unsigned long, origin)
>
> Here you converted offset_low from unsigned int to unsigned long. Hence
> you lost the clearing of the upper 32 bits. That would explain the bug.
> Any chance the process where the bug was seen was a compat process?

$ file /sbin/e2fsck
/sbin/e2fsck: ELF 32-bit MSB executable, MIPS, MIPS-I version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.8, with unknown capability 0x41000000 = 0xf676e75, stripped

> Patch below would probably fix it.

This patch works for me on the aforementioned Debian system.

> Btw. there are a lot of int->long conversions in the git commit
> mentioned above. AFAICS all(?) of the conversions are wrong.

> diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
> index 1a86f84..5abcc7f 100644
> --- a/arch/mips/kernel/linux32.c
> +++ b/arch/mips/kernel/linux32.c
> @@ -134,9 +134,9 @@ SYSCALL_DEFINE4(32_ftruncate64, unsigned long, fd, unsigned long, __dummy,
> return sys_ftruncate(fd, merge_64(a2, a3));
> }
>
> -SYSCALL_DEFINE5(32_llseek, unsigned long, fd, unsigned long, offset_high,
> - unsigned long, offset_low, loff_t __user *, result,
> - unsigned long, origin)
> +SYSCALL_DEFINE5(32_llseek, unsigned int, fd, unsigned int, offset_high,
> + unsigned int, offset_low, loff_t __user *, result,
> + unsigned int, origin)
> {
> return sys_llseek(fd, offset_high, offset_low, result, origin);
> }
>

--
dann frazier

2009-03-25 19:29:30

by dann frazier

Subject: Re: [PATCH 2/2] MIPS: o32: Get rid of useless wrapper for llseek

On Wed, Mar 25, 2009 at 01:15:55AM +0100, Ralf Baechle wrote:
> Signed-off-by: Ralf Baechle <[email protected]>

Tested-by: dann frazier <[email protected]>

> arch/mips/kernel/linux32.c | 7 -------
> arch/mips/kernel/scall64-o32.S | 2 +-
> 2 files changed, 1 insertions(+), 8 deletions(-)
>
> diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
> index 49aac6e..ab2da41 100644
> --- a/arch/mips/kernel/linux32.c
> +++ b/arch/mips/kernel/linux32.c
> @@ -133,13 +133,6 @@ SYSCALL_DEFINE4(32_ftruncate64, unsigned long, fd, unsigned long, __dummy,
> return sys_ftruncate(fd, merge_64(a2, a3));
> }
>
> -SYSCALL_DEFINE5(32_llseek, unsigned long, fd, unsigned long, offset_high,
> - unsigned long, offset_low, loff_t __user *, result,
> - unsigned long, origin)
> -{
> - return sys_llseek(fd, offset_high, offset_low, result, origin);
> -}
> -
> /* From the Single Unix Spec: pread & pwrite act like lseek to pos + op +
> lseek back to original location. They fail just like lseek does on
> non-seekable files. */
> diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
> index b0fef4f..d928614 100644
> --- a/arch/mips/kernel/scall64-o32.S
> +++ b/arch/mips/kernel/scall64-o32.S
> @@ -343,7 +343,7 @@ sys_call_table:
> PTR sys_ni_syscall /* for afs_syscall */
> PTR sys_setfsuid
> PTR sys_setfsgid
> - PTR sys_32_llseek /* 4140 */
> + PTR sys_llseek /* 4140 */
> PTR compat_sys_getdents
> PTR compat_sys_select
> PTR sys_flock
>

--
dann frazier