Commit Graph

8 Commits

Author SHA1 Message Date
Heiko Carstens 409d02ef6d x86: copy_from_user() should not return -EFAULT
Callers of copy_from_user() expect it to return the number of bytes
it could not copy. In no case it is supposed to return -EFAULT.

In case of a detected buffer overflow just return the requested
length. In addition one could think of a memset that would clear
the size of the target object.

[ hpa: code is not in .32 so not needed for -stable ]

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100105131911.GC5480@osiris.boeblingen.de.ibm.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-01-05 13:45:06 -08:00
Arjan van de Ven 63312b6a6f x86: Add a Kconfig option to turn the copy_from_user warnings into errors
For automated testing it is useful to have the option to turn
the warnings on copy_from_user() etc checks into errors:

 In function ‘copy_from_user’,
     inlined from ‘fd_copyin’ at drivers/block/floppy.c:3080,
     inlined from ‘fd_ioctl’ at drivers/block/floppy.c:3503:
   linux/arch/x86/include/asm/uaccess_32.h:213:
  error: call to ‘copy_from_user_overflow’ declared with attribute error:
  copy_from_user buffer size is not provably correct

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20091002075050.4e9f7641@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-02 19:01:42 +02:00
Arjan van de Ven 4a31276930 x86: Turn the copy_from_user check into an (optional) compile time warning
A previous patch added the buffer size check to copy_from_user().

One of the things learned from analyzing the result of the previous
patch is that in general, gcc is really good at proving that the
code contains sufficient security checks to not need to do a
runtime check. But that for those cases where gcc could not prove
this, there was a relatively high percentage of real security
issues.

This patch turns the case of "gcc cannot prove" into a compile time
warning, as long as a sufficiently new gcc is in use that supports
this. The objective is that these warnings will trigger developers
checking new cases out before a security hole enters a linux kernel
release.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <20090930130523.348ae6c4@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-01 11:31:04 +02:00
Arjan van de Ven 9f0cf4adb6 x86: Use __builtin_object_size() to validate the buffer size for copy_from_user()
gcc (4.x) supports the __builtin_object_size() builtin, which
reports the size of an object that a pointer point to, when known
at compile time. If the buffer size is not known at compile time, a
constant -1 is returned.

This patch uses this feature to add a sanity check to
copy_from_user(); if the target buffer is known to be smaller than
the copy size, the copy is aborted and a WARNing is emitted in
memory debug mode.

These extra checks compile away when the object size is not known,
or if both the buffer size and the copy length are constants.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20090926143301.2c396b94@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-26 16:25:41 +02:00
Sergey Senozhatsky 4fe487828b x86: Fix uaccess_32.h typo
Trivial: correct "that the we don't" typo.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
LKML-Reference: <20090917125401.GU3717@localdomain.by>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-20 20:19:34 +02:00
Ingo Molnar d1a76187a5 Merge commit 'v2.6.28-rc2' into core/locking
Conflicts:
	arch/um/include/asm/system.h
2008-10-28 16:54:49 +01:00
H. Peter Anvin 1965aae3c9 x86: Fix ASM_X86__ header guards
Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-10-22 22:55:23 -07:00
Al Viro bb8985586b x86, um: ... and asm-x86 move
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-10-22 22:55:20 -07:00