KMSAN: uninit-value in ppp_sync_receive

Status: fixed on 2024/01/29 09:26
Subsystems: ppp
[Documentation on labels]
Fix commit: 719639853d88 tty: Fix uninit-value access in ppp_sync_receive()
First crash: 998d, last: 991d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in ppp_sync_receive (2) ppp 7 1 728d 724d 0/29 auto-obsoleted due to no activity on 2024/11/12 06:29
upstream KMSAN: uninit-value in ppp_sync_receive (3) ppp 7 3 569d 596d 0/29 closed as invalid on 2025/02/20 20:55
upstream KMSAN: uninit-value in ppp_sync_receive (4) prio:high ppp 7 1 113d 109d 0/29 auto-obsoleted due to no activity on 2026/07/19 09:04

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in ppp_sync_input drivers/net/ppp/ppp_synctty.c:690 [inline]
BUG: KMSAN: uninit-value in ppp_sync_receive+0xd80/0xe70 drivers/net/ppp/ppp_synctty.c:334
 ppp_sync_input drivers/net/ppp/ppp_synctty.c:690 [inline]
 ppp_sync_receive+0xd80/0xe70 drivers/net/ppp/ppp_synctty.c:334
 tiocsti+0x32d/0x460 drivers/tty/tty_io.c:2295
 tty_ioctl+0x83c/0x1970 drivers/tty/tty_io.c:2694
 tty_compat_ioctl+0x6a6/0xce0
 __do_compat_sys_ioctl fs/ioctl.c:972 [inline]
 __se_compat_sys_ioctl+0x79b/0xfe0 fs/ioctl.c:914
 __ia32_compat_sys_ioctl+0x93/0xd0 fs/ioctl.c:914
 do_syscall_32_irqs_on arch/x86/entry/common.c:164 [inline]
 __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:230
 do_fast_syscall_32+0x37/0x70 arch/x86/entry/common.c:255
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:293
 entry_SYSENTER_compat_after_hwframe+0x70/0x7a

Uninit was created at:
 __alloc_pages+0x9a4/0xe00 mm/page_alloc.c:4591
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 __page_frag_cache_refill+0x99/0x2c0 mm/page_alloc.c:4691
 page_frag_alloc_align+0x94/0x590 mm/page_alloc.c:4722
 page_frag_alloc include/linux/gfp.h:322 [inline]
 __netdev_alloc_skb+0x218/0x700 net/core/skbuff.c:728
 netdev_alloc_skb include/linux/skbuff.h:3225 [inline]
 dev_alloc_skb include/linux/skbuff.h:3238 [inline]
 ppp_sync_input drivers/net/ppp/ppp_synctty.c:669 [inline]
 ppp_sync_receive+0x24f/0xe70 drivers/net/ppp/ppp_synctty.c:334
 tiocsti+0x32d/0x460 drivers/tty/tty_io.c:2295
 tty_ioctl+0x83c/0x1970 drivers/tty/tty_io.c:2694
 tty_compat_ioctl+0x6a6/0xce0
 __do_compat_sys_ioctl fs/ioctl.c:972 [inline]
 __se_compat_sys_ioctl+0x79b/0xfe0 fs/ioctl.c:914
 __ia32_compat_sys_ioctl+0x93/0xd0 fs/ioctl.c:914
 do_syscall_32_irqs_on arch/x86/entry/common.c:164 [inline]
 __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:230
 do_fast_syscall_32+0x37/0x70 arch/x86/entry/common.c:255
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:293
 entry_SYSENTER_compat_after_hwframe+0x70/0x7a

CPU: 1 PID: 5767 Comm: syz-executor.3 Not tainted 6.7.0-rc1-syzkaller-00012-g9bacdd8996c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
=====================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/11/14 22:02 upstream 9bacdd8996c7 cb976f63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386 KMSAN: uninit-value in ppp_sync_receive
2023/11/07 16:54 upstream be3ca57cfb77 83211397 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386 KMSAN: uninit-value in ppp_sync_receive
* Struck through repros no longer work on HEAD.