rbd: fix integer overflow in rbd_header_from_disk()
ondisk->snap_count is read from disk via rbd_req_sync_read() and thus needs validation. Otherwise, a bogus `snap_count' could overflow the kmalloc() size, leading to memory corruption. Also use `u32' consistently for `snap_count'. [elder@dreamhost.com: changed to use UINT_MAX rather than ULONG_MAX] Signed-off-by: Xi Wang <xi.wang@gmail.com> Reviewed-by: Alex Elder <elder@dreamhost.com>
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@ -487,16 +487,18 @@ static void rbd_coll_release(struct kref *kref)
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*/
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static int rbd_header_from_disk(struct rbd_image_header *header,
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struct rbd_image_header_ondisk *ondisk,
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int allocated_snaps,
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u32 allocated_snaps,
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gfp_t gfp_flags)
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{
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int i;
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u32 snap_count;
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u32 i, snap_count;
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if (memcmp(ondisk, RBD_HEADER_TEXT, sizeof(RBD_HEADER_TEXT)))
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return -ENXIO;
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snap_count = le32_to_cpu(ondisk->snap_count);
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if (snap_count > (UINT_MAX - sizeof(struct ceph_snap_context))
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/ sizeof (*ondisk))
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return -EINVAL;
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header->snapc = kmalloc(sizeof(struct ceph_snap_context) +
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snap_count * sizeof (*ondisk),
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gfp_flags);
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@ -1591,7 +1593,7 @@ static int rbd_read_header(struct rbd_device *rbd_dev,
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{
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ssize_t rc;
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struct rbd_image_header_ondisk *dh;
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int snap_count = 0;
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u32 snap_count = 0;
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u64 ver;
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size_t len;
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