[PATCH v2] seccomp: fix memory leak on filter attach
From: Kees Cook
Date: Wed Apr 16 2014 - 13:54:59 EST
This sets the correct error code when final filter memory is unavailable,
and frees the raw filter no matter what.
unreferenced object 0xffff8800d6ea4000 (size 512):
comm "sshd", pid 278, jiffies 4294898315 (age 46.653s)
hex dump (first 32 bytes):
21 00 00 00 04 00 00 00 15 00 01 00 3e 00 00 c0 !...........>...
06 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
backtrace:
[<ffffffff8151414e>] kmemleak_alloc+0x4e/0xb0
[<ffffffff811a3a40>] __kmalloc+0x280/0x320
[<ffffffff8110842e>] prctl_set_seccomp+0x11e/0x3b0
[<ffffffff8107bb6b>] SyS_prctl+0x3bb/0x4a0
[<ffffffff8152ef2d>] system_call_fastpath+0x1a/0x1f
[<ffffffffffffffff>] 0xffffffffffffffff
Reported-by: Masami Ichikawa <masami256@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Tested-by: Masami Ichikawa <masami256@xxxxxxxxx>
Acked-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
---
David, since you just pushed the a0-a5 fix, can you push this fix as well?
v2:
- drop stable cc, not needed.
- added tested-by and acked-by.
---
kernel/seccomp.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 590c37925084..b35c21503a36 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -255,6 +255,7 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
goto free_prog;
/* Allocate a new seccomp_filter */
+ ret = -ENOMEM;
filter = kzalloc(sizeof(struct seccomp_filter) +
sizeof(struct sock_filter_int) * new_len,
GFP_KERNEL|__GFP_NOWARN);
@@ -264,6 +265,7 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
ret = sk_convert_filter(fp, fprog->len, filter->insnsi, &new_len);
if (ret)
goto free_filter;
+ kfree(fp);
atomic_set(&filter->usage, 1);
filter->len = new_len;
--
1.7.9.5
--
Kees Cook
Chrome OS Security
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