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fuse: Don't access pipe->buffers without pipe_lock()

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fuse_dev_splice_write() reads pipe->buffers to determine the size of
'bufs' array before taking the pipe_lock(). This is not safe as
another thread might change the 'pipe->buffers' between the allocation
and taking the pipe_lock(). So we end up with too small 'bufs' array.

Move the bufs allocations inside pipe_lock()/pipe_unlock() to fix this.

Fixes: dd3bb14f44 ("fuse: support splice() writing to fuse device")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: <stable@vger.kernel.org> # v2.6.35
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Andrey Ryabinin 2018-07-17 19:00:33 +03:00 committed by Miklos Szeredi
parent 63576c13bd
commit a2477b0e67
1 changed files with 5 additions and 2 deletions
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7
fs/fuse/dev.c
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@ -1955,12 +1955,15 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
if (!fud) if (!fud)
return -EPERM; return -EPERM;
pipe_lock(pipe);
bufs = kmalloc_array(pipe->buffers, sizeof(struct pipe_buffer), bufs = kmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
GFP_KERNEL); GFP_KERNEL);
if (!bufs) if (!bufs) {
pipe_unlock(pipe);
return -ENOMEM; return -ENOMEM;
}
pipe_lock(pipe);
nbuf = 0; nbuf = 0;
rem = 0; rem = 0;
for (idx = 0; idx < pipe->nrbufs && rem < len; idx++) for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)