path: root/kernel/relay.c
diff options
authorJesper Juhl <>2007-07-31 00:39:18 -0700
committerLinus Torvalds <>2007-07-31 15:39:42 -0700
commitc9b3febc5b9c55a76b838c977b078195ec8bb95e (patch)
tree08745cc706021ec1586f8c7541a0218ab1764b08 /kernel/relay.c
parente804a4a4dd596d853f6d6f814fbdcf97b8efcdea (diff)
Fix a use after free bug in kernel->userspace relay file support
Coverity spotted what looks like a real possible case of using a variable after it has been freed. The problem is in kernel/relay.c::relay_open_buf() If the code hits "goto free_buf;" it ends up in this code : free_buf: relay_destroy_buf(buf); <--- calls kfree() on 'buf'. free_name: kfree(tmpname); end: return buf; <-- use after free of 'buf'. I read through the callers and they all handle a NULL return from this function as an error (and hitting the 'free_buf' label only happens on failure to chan->cb->create_buf_file(), so that looks like a clear error to me). The patch simply sets 'buf' to NULL after the call to relay_destroy_buf(buf); - as far as I can see that should take care of the problem. The patch also corrects a reference to a documentation file while I was at it. Note from Mathieu: the documentation reference change should have been done in a separate patch, but I guess no one will really care. Signed-off-by: Jesper Juhl <> Acked-by: "David J. Wilder" <> Tested-by: "David J. Wilder" <> Signed-off-by: Mathieu Desnoyers <> Cc: Tom Zanussi <> Cc: Karim Yaghmour <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'kernel/relay.c')
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/relay.c b/kernel/relay.c
index 510fbbd7b500..ad855017bc59 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -1,7 +1,7 @@
* Public API and common code for kernel->userspace relay file support.
- * See Documentation/filesystems/relayfs.txt for an overview of relayfs.
+ * See Documentation/filesystems/relay.txt for an overview.
* Copyright (C) 2002-2005 - Tom Zanussi (, IBM Corp
* Copyright (C) 1999-2005 - Karim Yaghmour (
@@ -426,6 +426,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
+ buf = NULL;