tree 833b6e7d88fc49bf430826db26f75b4877593a15
parent a1e85378ba50694cf8f27b190c7e16d7c8dad276
author Andrey Mirkin <amirkin@openvz.org> 1165465895 -0800
committer Linus Torvalds <torvalds@woody.osdl.org> 1165509560 -0800

[PATCH] skip data conversion in compat_sys_mount when data_page is NULL

OpenVZ Linux kernel team has found a problem with mounting in compat mode.

Simple command "mount -t smbfs ..." on Fedora Core 5 distro in 32-bit mode
leads to oops:

  Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP: compat_sys_mount+0xd6/0x290
  Process mount (pid: 14656, veid=300, threadinfo ffff810034d30000, task ffff810034c86bc0)
  Call Trace: ia32_sysret+0x0/0xa

The problem is that data_page pointer can be NULL, so we should skip data
conversion in this case.

Signed-off-by: Andrey Mirkin <amirkin@openvz.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>