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phonet: pep: do not write beyond optlen in getsockopt

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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: 02a47617cd ("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>
This commit is contained in:
Breno Leitao
2026-07-29 02:29:47 -07:00
committed by Jakub Kicinski
parent 6cd4e6c044
commit 77e5eb0e19
1 changed files with 1 additions and 1 deletions
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2
net/phonet/pep.c
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@@ -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;
}