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 <[email protected]>
Acked-by: "David J. Wilder" <[email protected]>
Tested-by: "David J. Wilder" <[email protected]>
Signed-off-by: Mathieu Desnoyers <[email protected]>
---
diff --git a/kernel/relay.c b/kernel/relay.c
index a615a8f..c55e399 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 ([email protected]), IBM Corp
* Copyright (C) 1999-2005 - Karim Yaghmour ([email protected])
@@ -427,6 +427,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
free_buf:
relay_destroy_buf(buf);
+ buf = NULL;
free_name:
kfree(tmpname);
end:
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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