bpf: Fix bpf_sk_select_reuseport() memory leak
[ Upstream commit b3af60928ab9129befa65e6df0310d27300942bf ]
As pointed out in the original comment, lookup in sockmap can return a TCP
ESTABLISHED socket. Such TCP socket may have had SO_ATTACH_REUSEPORT_EBPF
set before it was ESTABLISHED. In other words, a non-NULL sk_reuseport_cb
does not imply a non-refcounted socket.
Drop sk's reference in both error paths.
unreferenced object 0xffff888101911800 (size 2048):
comm "test_progs", pid 44109, jiffies 4297131437
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
80 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace (crc 9336483b):
__kmalloc_noprof+0x3bf/0x560
__reuseport_alloc+0x1d/0x40
reuseport_alloc+0xca/0x150
reuseport_attach_prog+0x87/0x140
sk_reuseport_attach_bpf+0xc8/0x100
sk_setsockopt+0x1181/0x1990
do_sock_setsockopt+0x12b/0x160
__sys_setsockopt+0x7b/0xc0
__x64_sys_setsockopt+0x1b/0x30
do_syscall_64+0x93/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
BUG=b/394276367
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2025-21683 in the Linux kernel.
cos-patch: security-moderate
Fixes: 64d85290d79c ("bpf: Allow bpf_map_lookup_elem for SOCKMAP and SOCKHASH")
Change-Id: Ib03e0bdf3ce806e13ce8521142c3f880d04f9349
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Reviewed-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250110-reuseport-memleak-v1-1-fa1ddab0adfe@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kernel CVE Triage Automation <cloud-image-kernel-cve-triage-automation@prod.google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/92040
Reviewed-by: Kevin Berry <kpberry@google.com>
Reviewed-by: Michael Kochera <kochera@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
1 file changed
