|author||Jesper Juhl <firstname.lastname@example.org>||2007-07-31 00:39:18 -0700|
|committer||Linus Torvalds <email@example.com>||2007-07-31 15:39:42 -0700|
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 <firstname.lastname@example.org> Acked-by: "David J. Wilder" <email@example.com> Tested-by: "David J. Wilder" <firstname.lastname@example.org> Signed-off-by: Mathieu Desnoyers <email@example.com> Cc: Tom Zanussi <firstname.lastname@example.org> Cc: Karim Yaghmour <email@example.com> Signed-off-by: Andrew Morton <firstname.lastname@example.org> Signed-off-by: Linus Torvalds <email@example.com>
Diffstat (limited to 'kernel/relay.c')
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/relay.c b/kernel/relay.c
index 510fbbd7b50..ad855017bc5 100644
@@ -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 (firstname.lastname@example.org), IBM Corp
* Copyright (C) 1999-2005 - Karim Yaghmour (email@example.com)
@@ -426,6 +426,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
+ buf = NULL;