proc: fix oops on invalid /proc/<pid>/maps access
authorLinus Torvalds <torvalds@linux-foundation.org>
Mon, 28 Mar 2011 02:09:29 +0000 (19:09 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 28 Mar 2011 02:09:29 +0000 (19:09 -0700)
commit76597cd31470fa130784c78fadb4dab2e624a723
tree94387f243f4b8211352a95fda5b23bd12bbf8873
parent16c29dafcc86024048f1dbb8349d31cb22c7c55a
proc: fix oops on invalid /proc/<pid>/maps access

When m_start returns an error, the seq_file logic will still call m_stop
with that error entry, so we'd better make sure that we check it before
using it as a vma.

Introduced by commit ec6fd8a4355c ("report errors in /proc/*/*map*
sanely"), which replaced NULL with various ERR_PTR() cases.

(On ia64, you happen to get a unaligned fault instead of a page fault,
since the address used is generally some random error code like -EPERM)

Reported-by: Anca Emanuel <anca.emanuel@gmail.com>
Reported-by: Tony Luck <tony.luck@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Américo Wang <xiyou.wangcong@gmail.com>
Cc: Stephen Wilson <wilsons@start.ca>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/proc/task_mmu.c