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Michael BommaritoandGreg Kroah-Hartman
f14e87d7b1
commitbd910a7660upstream. recv_dless_read() receives a P_DATA_REPLY from a peer into the bio of an outstanding read request. The peer-supplied payload length reaches it as the signed int data_size, and two peer-controlled inputs can make it negative. With a negotiated data-integrity-alg the digest length is subtracted first, so a reply whose payload is smaller than the digest underflows data_size. With no integrity algorithm (the default) data_size is assigned from the unsigned h95/h100 wire length and drbdd() never bounds it for a payload-carrying command, so a length above INT_MAX casts it negative; this path needs no non-default feature. The bio receive loop then computes expect = min_t(int, data_size, bv_len), which is negative, and drbd_recv_all_warn(mapped, expect) receives with a size_t of SIZE_MAX into the first mapped page. The sibling receive path read_in_block() is not affected: it uses an unsigned size and rejects it against DRBD_MAX_BIO_SIZE before receiving. Reject a data reply whose size is negative after the optional digest subtraction, covering both triggers. Impact: a malicious or man-in-the-middle DRBD peer copies attacker-chosen bytes past a bio page in the receiver, corrupting kernel memory. A node that reads from its peer (a diskless node, or read-balancing to the peer) is exposed in the default configuration; data-integrity-alg is not required. Fixes:b411b3637f("The DRBD driver") Cc: stable@vger.kernel.org Assisted-by: Codex:gpt-5-5-xhigh Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com> Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> Link: https://patch.msgid.link/20260710022837.3738461-1-michael.bommarito@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>