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9p: virtio: fix unlikely null pointer deref in handle_rerror

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[ Upstream commit 13ade4ac5c28e8a014fa85278f5a4270b215f906 ]

handle_rerror can dereference the pages pointer, but it is not
necessarily set for small payloads.
In practice these should be filtered out by the size check, but
might as well double-check explicitly.

This fixes the following scan-build warnings:
net/9p/trans_virtio.c:401:24: warning: Dereference of null pointer [core.NullDereference]
                memcpy_from_page(to, *pages++, offs, n);
                                     ^~~~~~~~
net/9p/trans_virtio.c:406:23: warning: Dereference of null pointer (loaded from variable 'pages') [core.NullDereference]
        memcpy_from_page(to, *pages, offs, size);
                             ^~~~~~

Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Dominique Martinet 2023-05-03 16:49:26 +09:00 committed by Greg Kroah-Hartman
parent 72c90ebb2d
commit 05d88512e8
1 changed files with 1 additions and 1 deletions
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net/9p/trans_virtio.c
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@ -385,7 +385,7 @@ static void handle_rerror(struct p9_req_t *req, int in_hdr_len,
void *to = req->rc.sdata + in_hdr_len;
// Fits entirely into the static data? Nothing to do.
if (req->rc.size < in_hdr_len)
if (req->rc.size < in_hdr_len || !pages)
return;
// Really long error message? Tough, truncate the reply. Might get