From 77e5eb0e192aec6710c03ca8144582fd2af36ca4 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Wed, 29 Jul 2026 02:29:47 -0700 Subject: [PATCH] phonet: pep: do not write beyond optlen in getsockopt MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Joe Damato Acked-by: Stanislav Fomichev Signed-off-by: Breno Leitao Link: https://patch.msgid.link/20260729-getsockopt_phase4-v4-4-c44576757c17@debian.org Signed-off-by: Jakub Kicinski --- net/phonet/pep.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/phonet/pep.c b/net/phonet/pep.c index 31b29e3ca7bc..e188c563ee5b 100644 --- a/net/phonet/pep.c +++ b/net/phonet/pep.c @@ -1117,7 +1117,7 @@ static int pep_getsockopt(struct sock *sk, int level, int optname, len = min_t(unsigned int, sizeof(int), len); if (put_user(len, optlen)) return -EFAULT; - if (put_user(val, (int __user *) optval)) + if (copy_to_user(optval, &val, len)) return -EFAULT; return 0; }