phonet: pep: do not write beyond optlen in getsockopt

pep_getsockopt() clamps the reported length to the caller's buffer with
min_t(), but then stores the value with put_user(val, (int __user *)
optval), which always writes sizeof(int) bytes. A getsockopt() call with
an optlen smaller than sizeof(int) thus reports the clamped length yet
writes a full int, one to three bytes past the user buffer.

Write the value with copy_to_user() bounded by len, so at most optlen
bytes are copied, matching the length reported back to userspace.

Fixes: 02a47617cdce ("Phonet: implement GPRS virtual interface over PEP socket")
Acked-by: Rémi Denis-Courmont <remi@remlab.net>
Reviewed-by: Joe Damato <joe@dama.to>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260729-getsockopt_phase4-v4-4-c44576757c17@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions