[PATCH] apparmor: check address length before reading AF_UNSPEC bind address

[sashiko-bot at kernel.org]

> bind_map_addr() handles AF_UNSPEC on an IPv4 socket by reading
> addr4->sin_addr.s_addr to check for INADDR_ANY. At that point the only
> length check done is addrlen >= offsetofend(struct sockaddr, sa_family),
> i.e. 2 bytes, while sin_addr sits at offset 4. move_addr_to_kernel()
> copies only addrlen bytes into the on-stack sockaddr_storage, so a
> bind() with a short AF_UNSPEC address makes AppArmor branch on bytes the
> caller never supplied.
> 
> Depending on those bytes, a confined task gets -EAFNOSUPPORT instead of
> the -EINVAL that inet_bind_sk() returns for the same request. Kernels
> built with CONFIG_INIT_STACK_ALL_ZERO read zeroes and happen to behave
> correctly.
> 
> Check the length first, as inet_bind_sk() does, and as the AF_INET6
> case above already does for inet6_bind_sk().
> 
> Fixes: 89ac6aa752ec ("apparmor: push inet mediation into profile callbacks, and improve auditing")
> Cc: stable at vger.kernel.org
> Assisted-by: LLM
> Signed-off-by: Michail Andreas Michalopoulos <mike.michalo at gmail.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261020140030.92643-1-mike.michalo@gmail.com?part=1