Exploit Report

Computer Security And Bug Information

CVE-2024-26676

CVECVE-2024-26676
CVE Title
Published Date2024-04-02T07:15Z
Modified Date2024-04-02T12:50Z
DescriptionIn the Linux kernel, the following vulnerability has been resolved: af_unix: Call kfree_skb() for dead unix_(sk)->oob_skb in GC. syzbot reported a warning [0] in __unix_gc() with a repro, which creates a socketpair and sends one socket's fd to itself using the peer. socketpair(AF_UNIX, SOCK_STREAM, 0, [3, 4]) = 0 sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="360", iov_len=1}], msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, cmsg_data=[3]}], msg_controllen=24, msg_flags=0}, MSG_OOB|MSG_PROBE|MSG_DONTWAIT|MSG_ZEROCOPY) = 1 This forms a self-cyclic reference that GC should finally untangle but does not due to lack of MSG_OOB handling, resulting in memory leak. Recently, commit 11498715f266 ("af_unix: Remove io_uring code for GC.") removed io_uring's dead code in GC and revealed the problem. The code was executed at the final stage of GC and unconditionally moved all GC candidates from gc_candidates to gc_inflight_list. That papered over the reported problem by always making the following WARN_ON_ONCE(!list_empty(&gc_candidates)) false. The problem has been there since commit 2aab4b969002 ("af_unix: fix struct pid leaks in OOB support") added full scm support for MSG_OOB while fixing another bug. To fix this problem, we must call kfree_skb() for unix_sk(sk)->oob_skb if the socket still exists in gc_candidates after purging collected skb. Then, we need to set NULL to oob_skb before calling kfree_skb() because it calls last fput() and triggers unix_release_sock(), where we call duplicate kfree_skb(u->oob_skb) if not NULL. Note that the leaked socket remained being linked to a global list, so kmemleak also could not detect it. We need to check /proc/net/protocol to notice the unfreed socket. [0]: WARNING: CPU: 0 PID: 2863 at net/unix/garbage.c:345 __unix_gc+0xc74/0xe80 net/unix/garbage.c:345 Modules linked in: CPU: 0 PID: 2863 Comm: kworker/u4:11 Not tainted 6.8.0-rc1-syzkaller-00583-g1701940b1a02 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 Workqueue: events_unbound __unix_gc RIP: 0010:__unix_gc+0xc74/0xe80 net/unix/garbage.c:345 Code: 8b 5c 24 50 e9 86 f8 ff ff e8 f8 e4 22 f8 31 d2 48 c7 c6 30 6a 69 89 4c 89 ef e8 97 ef ff ff e9 80 f9 ff ff e8 dd e4 22 f8 90 <0f> 0b 90 e9 7b fd ff ff 48 89 df e8 5c e7 7c f8 e9 d3 f8 ff ff e8 RSP: 0018:ffffc9000b03fba0 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffffc9000b03fc10 RCX: ffffffff816c493e RDX: ffff88802c02d940 RSI: ffffffff896982f3 RDI: ffffc9000b03fb30 RBP: ffffc9000b03fce0 R08: 0000000000000001 R09: fffff52001607f66 R10: 0000000000000003 R11: 0000000000000002 R12: dffffc0000000000 R13: ffffc9000b03fc10 R14: ffffc9000b03fc10 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005559c8677a60 CR3: 000000000d57a000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: process_one_work+0x889/0x15e0 kernel/workqueue.c:2633 process_scheduled_works kernel/workqueue.c:2706 [inline] worker_thread+0x8b9/0x12a0 kernel/workqueue.c:2787 kthread+0x2c6/0x3b0 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242
References
By clicking these links you will leave this website. We do not endorse and will not be held accountable for any activity on external sites.
Reference URLhttps://git.kernel.org/stable/c/4fe505c63aa3273135a57597fda761e9aecc7668
Reference Description https://git.kernel.org/stable/c/4fe505c63aa3273135a57597fda761e9aecc7668
Reference URLhttps://git.kernel.org/stable/c/e0e09186d8821ad59806115d347ea32efa43ca4b
Reference Description https://git.kernel.org/stable/c/e0e09186d8821ad59806115d347ea32efa43ca4b
Reference URLhttps://git.kernel.org/stable/c/b74aa9ce13d02b7fd37c5325b99854f91b9b4276
Reference Description https://git.kernel.org/stable/c/b74aa9ce13d02b7fd37c5325b99854f91b9b4276
Reference URLhttps://git.kernel.org/stable/c/82ae47c5c3a6b27fdc0f9e83c1499cb439c56140
Reference Description https://git.kernel.org/stable/c/82ae47c5c3a6b27fdc0f9e83c1499cb439c56140
Reference URLhttps://git.kernel.org/stable/c/1279f9d9dec2d7462823a18c29ad61359e0a007d
Reference Description https://git.kernel.org/stable/c/1279f9d9dec2d7462823a18c29ad61359e0a007d
Sources NIST MITRE
Note
  • No CVSS data for this CVE

This site's data is aggregated programmatically and provided "as is" without any representations or warranties, express or implied. Exploit.report is not affiliated with the The MITRE Corporation, U.S. Department of Homeland Security (DHS), Cybersecurity and Infrastructure Security Agency (CISA), or US government in any way. CVE and the CVE logo are registered trademarks of The MITRE Corporation

© 2022 Exploit.Report | Data | Contact | Privacy Policy | Articles