Re: [PATCH] net: qrtr: fix 32-bit integer overflow in qrtr_endpoint_post()

[Simon Horman]

On Thu, Jun 11, 2026 at 08:54:55AM -0400, Michael Bommarito wrote:
> qrtr_endpoint_post() validates an incoming packet with
> 
> 	if (!size || len != ALIGN(size, 4) + hdrlen)
> 		goto err;
> 
> where size comes from the wire. On 32-bit, size_t is 32 bits and
> ALIGN(size, 4) wraps to 0 for size >= 0xfffffffd, so the check
> passes and skb_put_data(skb, data + hdrlen, size) writes past the
> hdrlen-sized skb and oopses the kernel. 64-bit is unaffected.
> 
> This is the 32-bit residual of ad9d24c9429e2 ("net: qrtr: fix OOB
> Read in qrtr_endpoint_post"), which fixed only the 64-bit case.
> 
> Reject any size that cannot fit the buffer before the ALIGN.
> 
> Fixes: ad9d24c9429e2 ("net: qrtr: fix OOB Read in qrtr_endpoint_post")
> Cc: stable@xxxxxxxxxxxxxxx
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Michael Bommarito <michael.bommarito@xxxxxxxxx>
> ---
> 32-bit only; reachable via /dev/qrtr-tun (CONFIG_QRTR_TUN) or a QMI modem.
> Reproduced on i386 (a 32-byte write with size 0xfffffffd faults; well-formed
> writes are unaffected).  QRTR mostly runs on 64-bit now, so this is a
> correctness fix completing ad9d24c9429e2, not a high-severity bug.

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>