Hello,
syzbot found the following issue on:
HEAD commit: 5ff2756a Merge tag 'nfs-for-5.13-2' of git://git.linux-nfs.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11815dabd00000 kernel config: https://syzkaller.appspot.com/x/.config?x=770708ea7cfd4916 dashboard link: https://syzkaller.appspot.com/bug?extid=c3a706cec1ea99e1c693 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15b5b4b5d00000
Bisection is inconclusive: the issue happens on the oldest tested release.
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10638a6bd00000 final oops: https://syzkaller.appspot.com/x/report.txt?x=12638a6bd00000 console output: https://syzkaller.appspot.com/x/log.txt?x=14638a6bd00000
IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c3a706cec1ea99e1c693@syzkaller.appspotmail.com
================================================================== BUG: KASAN: use-after-free in drm_getunique+0x23b/0x2a0 drivers/gpu/drm/drm_ioctl.c:124 Read of size 4 at addr ffff8880212cb818 by task syz-executor.0/8693
CPU: 1 PID: 8693 Comm: syz-executor.0 Not tainted 5.13.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:233 __kasan_report mm/kasan/report.c:419 [inline] kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:436 drm_getunique+0x23b/0x2a0 drivers/gpu/drm/drm_ioctl.c:124 drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787 drm_ioctl+0x4fd/0x9b0 drivers/gpu/drm/drm_ioctl.c:887 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl fs/ioctl.c:1055 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665d9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc47c368188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665d9 RDX: 0000000020000180 RSI: 00000000c0145401 RDI: 0000000000000003 RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038 R13: 00007fff26bf6f4f R14: 00007fc47c368300 R15: 0000000000022000
Allocated by task 8692: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:428 [inline] ____kasan_kmalloc mm/kasan/common.c:507 [inline] ____kasan_kmalloc mm/kasan/common.c:466 [inline] __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:516 kmalloc include/linux/slab.h:556 [inline] kzalloc include/linux/slab.h:686 [inline] drm_master_create+0x40/0x4f0 drivers/gpu/drm/drm_auth.c:107 drm_new_set_master+0xd2/0x400 drivers/gpu/drm/drm_auth.c:143 drm_master_open+0x13e/0x1a0 drivers/gpu/drm/drm_auth.c:306 drm_open_helper drivers/gpu/drm/drm_file.c:355 [inline] drm_open+0x6b4/0xb10 drivers/gpu/drm/drm_file.c:430 drm_stub_open+0x281/0x530 drivers/gpu/drm/drm_drv.c:1015 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c0e/0x27e0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1187 do_sys_open fs/open.c:1203 [inline] __do_sys_openat fs/open.c:1219 [inline] __se_sys_openat fs/open.c:1214 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1214 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae
Freed by task 8692: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357 ____kasan_slab_free mm/kasan/common.c:360 [inline] ____kasan_slab_free mm/kasan/common.c:325 [inline] __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:368 kasan_slab_free include/linux/kasan.h:212 [inline] slab_free_hook mm/slub.c:1582 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1607 slab_free mm/slub.c:3167 [inline] kfree+0xe5/0x7f0 mm/slub.c:4217 kref_put include/linux/kref.h:65 [inline] drm_master_put drivers/gpu/drm/drm_auth.c:399 [inline] drm_new_set_master+0x314/0x400 drivers/gpu/drm/drm_auth.c:155 drm_setmaster_ioctl+0x3de/0x550 drivers/gpu/drm/drm_auth.c:240 drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787 drm_ioctl+0x4fd/0x9b0 drivers/gpu/drm/drm_ioctl.c:887 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl fs/ioctl.c:1055 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae
The buggy address belongs to the object at ffff8880212cb800 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 24 bytes inside of 512-byte region [ffff8880212cb800, ffff8880212cba00) The buggy address belongs to the page: page:ffffea000084b200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x212c8 head:ffffea000084b200 order:2 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888011041c80 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 8440, ts 58973220338, free_ts 58965641961 prep_new_page mm/page_alloc.c:2358 [inline] get_page_from_freelist+0x1033/0x2b60 mm/page_alloc.c:3994 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5200 alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272 alloc_slab_page mm/slub.c:1645 [inline] allocate_slab+0x2c5/0x4c0 mm/slub.c:1785 new_slab mm/slub.c:1848 [inline] new_slab_objects mm/slub.c:2594 [inline] ___slab_alloc+0x4a1/0x810 mm/slub.c:2757 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2797 slab_alloc_node mm/slub.c:2879 [inline] slab_alloc mm/slub.c:2921 [inline] __kmalloc+0x315/0x330 mm/slub.c:4055 kmalloc include/linux/slab.h:561 [inline] kzalloc include/linux/slab.h:686 [inline] tomoyo_init_log+0x1376/0x1ee0 security/tomoyo/audit.c:275 tomoyo_supervisor+0x34d/0xf00 security/tomoyo/common.c:2097 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline] tomoyo_path_permission security/tomoyo/file.c:587 [inline] tomoyo_path_permission+0x270/0x3a0 security/tomoyo/file.c:573 tomoyo_path_perm+0x2f0/0x400 security/tomoyo/file.c:838 security_inode_getattr+0xcf/0x140 security/security.c:1332 vfs_getattr fs/stat.c:139 [inline] vfs_statx+0x164/0x390 fs/stat.c:207 vfs_fstatat fs/stat.c:225 [inline] vfs_lstat include/linux/fs.h:3384 [inline] __do_sys_newlstat+0x91/0x110 fs/stat.c:380 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1298 [inline] __free_pages_ok+0x476/0xce0 mm/page_alloc.c:1572 stack_depot_save+0x162/0x4e0 lib/stackdepot.c:336 kasan_save_stack+0x32/0x40 mm/kasan/common.c:40 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:428 [inline] ____kasan_kmalloc mm/kasan/common.c:507 [inline] ____kasan_kmalloc mm/kasan/common.c:466 [inline] __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:516 kmalloc include/linux/slab.h:556 [inline] kzalloc include/linux/slab.h:686 [inline] batadv_bla_get_backbone_gw+0xb8/0xb00 net/batman-adv/bridge_loop_avoidance.c:502 batadv_bla_update_own_backbone_gw net/batman-adv/bridge_loop_avoidance.c:565 [inline] batadv_bla_tx+0x15d/0x24d0 net/batman-adv/bridge_loop_avoidance.c:2100 batadv_interface_tx+0x45b/0x1660 net/batman-adv/soft-interface.c:238 __netdev_start_xmit include/linux/netdevice.h:4944 [inline] netdev_start_xmit include/linux/netdevice.h:4958 [inline] xmit_one net/core/dev.c:3654 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3670 __dev_queue_xmit+0x2133/0x3130 net/core/dev.c:4246 neigh_resolve_output net/core/neighbour.c:1495 [inline] neigh_resolve_output+0x50e/0x820 net/core/neighbour.c:1475 neigh_output include/net/neighbour.h:510 [inline] ip6_finish_output2+0x6ee/0x1700 net/ipv6/ip6_output.c:117 __ip6_finish_output net/ipv6/ip6_output.c:182 [inline] __ip6_finish_output+0x4c1/0xe10 net/ipv6/ip6_output.c:161 ip6_finish_output+0x35/0x200 net/ipv6/ip6_output.c:192 NF_HOOK_COND include/linux/netfilter.h:290 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:215 dst_output include/net/dst.h:448 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ndisc_send_skb+0xa99/0x1750 net/ipv6/ndisc.c:508 ndisc_send_ns+0x3a9/0x840 net/ipv6/ndisc.c:650
Memory state around the buggy address: ffff8880212cb700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880212cb780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880212cb800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff8880212cb880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880212cb900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
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