[v2.6.34-stable 194/213] Remove user-triggerable BUG from mpol_to_str

From: Paul Gortmaker
Date: Wed Feb 05 2014 - 15:16:26 EST


From: Dave Jones <davej@xxxxxxxxxx>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------

commit 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a upstream.

Trivially triggerable, found by trinity:

kernel BUG at mm/mempolicy.c:2546!
Process trinity-child2 (pid: 23988, threadinfo ffff88010197e000, task ffff88007821a670)
Call Trace:
show_numa_map+0xd5/0x450
show_pid_numa_map+0x13/0x20
traverse+0xf2/0x230
seq_read+0x34b/0x3e0
vfs_read+0xac/0x180
sys_pread64+0xa2/0xc0
system_call_fastpath+0x1a/0x1f
RIP: mpol_to_str+0x156/0x360

Signed-off-by: Dave Jones <davej@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
mm/mempolicy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index ae43da3aff5a..1d5c89a7e128 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2330,7 +2330,7 @@ int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context)
break;

default:
- BUG();
+ return -EINVAL;
}

l = strlen(policy_types[mode]);
--
1.8.5.2

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