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authorLinus Torvalds <torvalds@linux-foundation.org>2011-04-18 10:35:30 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2011-04-21 14:32:52 -0700
commitc8b265db1e63fdb296ec2721f5c1473c44bc4dc5 (patch)
treeef932aa910796d144dbe99a85d2d9123167c8705 /kernel
parentdd8eece9b71a865b6f223c2f84058788870cd655 (diff)
next_pidmap: fix overflow condition
commit c78193e9c7bcbf25b8237ad0dec82f805c4ea69b upstream. next_pidmap() just quietly accepted whatever 'last' pid that was passed in, which is not all that safe when one of the users is /proc. Admittedly the proc code should do some sanity checking on the range (and that will be the next commit), but that doesn't mean that the helper functions should just do that pidmap pointer arithmetic without checking the range of its arguments. So clamp 'last' to PID_MAX_LIMIT. The fact that we then do "last+1" doesn't really matter, the for-loop does check against the end of the pidmap array properly (it's only the actual pointer arithmetic overflow case we need to worry about, and going one bit beyond isn't going to overflow). [ Use PID_MAX_LIMIT rather than pid_max as per Eric Biederman ] Reported-by: Tavis Ormandy <taviso@cmpxchg8b.com> Analyzed-by: Robert Święcki <robert@swiecki.net> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/pid.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/pid.c b/kernel/pid.c
index 39b65b69584..6aeebc20d34 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -217,11 +217,14 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
return -1;
}
-int next_pidmap(struct pid_namespace *pid_ns, int last)
+int next_pidmap(struct pid_namespace *pid_ns, unsigned int last)
{
int offset;
struct pidmap *map, *end;
+ if (last >= PID_MAX_LIMIT)
+ return -1;
+
offset = (last + 1) & BITS_PER_PAGE_MASK;
map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE];
end = &pid_ns->pidmap[PIDMAP_ENTRIES];