x86: fix error handling for 32-bit compat out-of-range system call numbers
authorLinus Torvalds <torvalds@linux-foundation.org>
Thu, 13 Aug 2015 23:19:44 +0000 (16:19 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 13 Aug 2015 23:19:44 +0000 (16:19 -0700)
commitcd88ec2317015f9ae94fa55149bc6f61e1a460e9
tree6f5e066cfb60b8d6dfb1a9b806e69cdfd7c1a3c2
parent5b3e2e14eaa2a98232a4f292341fb88438685734
x86: fix error handling for 32-bit compat out-of-range system call numbers

Commit 3f5159a9221f ("x86/asm/entry/32: Update -ENOSYS handling to match
the 64-bit logic") broke the ENOSYS handling for the 32-bit compat case.
The proper error return value was never loaded into %rax, except if
things just happened to go through the audit paths, which ended up
reloading the return value.

This moves the loading or %rax into the normal system call path, just to
make sure the error case triggers it.  It's kind of sad, since it adds a
useless instruction to reload the register to the fast path, but it's
not like that single load from the stack is going to be noticeable.

Reported-by: David Drysdale <drysdale@google.com>
Tested-by: Kees Cook <keescook@chromium.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/x86/entry/entry_64_compat.S