On Thu, Oct 3, 2024 at 3:44 PM syzbot <syzbot+4c0d0c4cde787116d465@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot has tested the proposed patch but the reproducer is still triggering an issue: > KASAN: slab-use-after-free Write in sco_sock_timeout > > ================================================================== > BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline] > BUG: KASAN: slab-use-after-free in atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline] > BUG: KASAN: slab-use-after-free in __refcount_add include/linux/refcount.h:184 [inline] > BUG: KASAN: slab-use-after-free in __refcount_inc include/linux/refcount.h:241 [inline] > BUG: KASAN: slab-use-after-free in refcount_inc include/linux/refcount.h:258 [inline] > BUG: KASAN: slab-use-after-free in sock_hold include/net/sock.h:781 [inline] > BUG: KASAN: slab-use-after-free in sco_sock_timeout+0x8b/0x270 net/bluetooth/sco.c:92 > Write of size 4 at addr ffff88802639a080 by task kworker/1:2/1808 This really doesn't make much sense, it seems this is catching a UAF on sock_hold but the backtrace shows it was freed with skb_free, even if the memory was reclaimed and then reallocated that would just it more difficult to find out why this is happening. > CPU: 1 UID: 0 PID: 1808 Comm: kworker/1:2 Not tainted 6.12.0-rc1-syzkaller-00113-g8c245fe7dde3-dirty #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 > Workqueue: events sco_sock_timeout > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:377 [inline] > print_report+0x169/0x550 mm/kasan/report.c:488 > kasan_report+0x143/0x180 mm/kasan/report.c:601 > kasan_check_range+0x282/0x290 mm/kasan/generic.c:189 > instrument_atomic_read_write include/linux/instrumented.h:96 [inline] > atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline] > __refcount_add include/linux/refcount.h:184 [inline] > __refcount_inc include/linux/refcount.h:241 [inline] > refcount_inc include/linux/refcount.h:258 [inline] > sock_hold include/net/sock.h:781 [inline] > sco_sock_timeout+0x8b/0x270 net/bluetooth/sco.c:92 > process_one_work kernel/workqueue.c:3229 [inline] > process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310 > worker_thread+0x870/0xd30 kernel/workqueue.c:3391 > kthread+0x2f2/0x390 kernel/kthread.c:389 > ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > </TASK> > > Allocated by task 25: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 > poison_kmalloc_redzone mm/kasan/common.c:377 [inline] > __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394 > kasan_kmalloc include/linux/kasan.h:257 [inline] > __do_kmalloc_node mm/slub.c:4265 [inline] > __kmalloc_node_track_caller_noprof+0x225/0x440 mm/slub.c:4284 > kmalloc_reserve+0x111/0x2a0 net/core/skbuff.c:609 > __alloc_skb+0x1f3/0x440 net/core/skbuff.c:678 > alloc_skb include/linux/skbuff.h:1322 [inline] > nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline] > nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline] > nsim_dev_trap_report_work+0x254/0xaa0 drivers/net/netdevsim/dev.c:850 > process_one_work kernel/workqueue.c:3229 [inline] > process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310 > worker_thread+0x870/0xd30 kernel/workqueue.c:3391 > kthread+0x2f2/0x390 kernel/kthread.c:389 > ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > Freed by task 25: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 > kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579 > poison_slab_object mm/kasan/common.c:247 [inline] > __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 > kasan_slab_free include/linux/kasan.h:230 [inline] > slab_free_hook mm/slub.c:2343 [inline] > slab_free mm/slub.c:4580 [inline] > kfree+0x1a0/0x440 mm/slub.c:4728 > skb_kfree_head net/core/skbuff.c:1086 [inline] > skb_free_head net/core/skbuff.c:1098 [inline] > skb_release_data+0x6a0/0x8a0 net/core/skbuff.c:1125 > skb_release_all net/core/skbuff.c:1190 [inline] > __kfree_skb net/core/skbuff.c:1204 [inline] > consume_skb+0x9f/0xf0 net/core/skbuff.c:1436 > nsim_dev_trap_report drivers/net/netdevsim/dev.c:821 [inline] > nsim_dev_trap_report_work+0x765/0xaa0 drivers/net/netdevsim/dev.c:850 > process_one_work kernel/workqueue.c:3229 [inline] > process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310 > worker_thread+0x870/0xd30 kernel/workqueue.c:3391 > kthread+0x2f2/0x390 kernel/kthread.c:389 > ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > The buggy address belongs to the object at ffff88802639a000 > which belongs to the cache kmalloc-4k of size 4096 > The buggy address is located 128 bytes inside of > freed 4096-byte region [ffff88802639a000, ffff88802639b000) > > The buggy address belongs to the physical page: > page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x26398 > head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 > flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) > page_type: f5(slab) > raw: 00fff00000000040 ffff888015442140 dead000000000122 0000000000000000 > raw: 0000000000000000 0000000000040004 00000001f5000000 0000000000000000 > head: 00fff00000000040 ffff888015442140 dead000000000122 0000000000000000 > head: 0000000000000000 0000000000040004 00000001f5000000 0000000000000000 > head: 00fff00000000003 ffffea000098e601 ffffffffffffffff 0000000000000000 > head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5398, tgid 5398 (udevd), ts 123333990998, free_ts 123322335448 > set_page_owner include/linux/page_owner.h:32 [inline] > post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1537 > prep_new_page mm/page_alloc.c:1545 [inline] > get_page_from_freelist+0x3045/0x3190 mm/page_alloc.c:3457 > __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4733 > alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265 > alloc_slab_page+0x6a/0x120 mm/slub.c:2413 > allocate_slab+0x5a/0x2f0 mm/slub.c:2579 > new_slab mm/slub.c:2632 [inline] > ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3819 > __slab_alloc+0x58/0xa0 mm/slub.c:3909 > __slab_alloc_node mm/slub.c:3962 [inline] > slab_alloc_node mm/slub.c:4123 [inline] > __do_kmalloc_node mm/slub.c:4264 [inline] > __kmalloc_noprof+0x25a/0x400 mm/slub.c:4277 > kmalloc_noprof include/linux/slab.h:882 [inline] > tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251 > tomoyo_get_realpath security/tomoyo/file.c:151 [inline] > tomoyo_path2_perm+0x3eb/0xbb0 security/tomoyo/file.c:923 > tomoyo_path_rename+0x198/0x1e0 security/tomoyo/hooks.h:274 > security_path_rename+0x266/0x4e0 security/security.c:2020 > do_renameat2+0x94a/0x13f0 fs/namei.c:5157 > __do_sys_rename fs/namei.c:5217 [inline] > __se_sys_rename fs/namei.c:5215 [inline] > __x64_sys_rename+0x82/0x90 fs/namei.c:5215 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > page last free pid 4548 tgid 4548 stack trace: > reset_page_owner include/linux/page_owner.h:25 [inline] > free_pages_prepare mm/page_alloc.c:1108 [inline] > free_unref_page+0xcfb/0xf20 mm/page_alloc.c:2638 > __slab_free+0x31b/0x3d0 mm/slub.c:4491 > qlink_free mm/kasan/quarantine.c:163 [inline] > qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179 > kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286 > __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329 > kasan_slab_alloc include/linux/kasan.h:247 [inline] > slab_post_alloc_hook mm/slub.c:4086 [inline] > slab_alloc_node mm/slub.c:4135 [inline] > __do_kmalloc_node mm/slub.c:4264 [inline] > __kmalloc_noprof+0x1a6/0x400 mm/slub.c:4277 > kmalloc_noprof include/linux/slab.h:882 [inline] > tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251 > tomoyo_get_realpath security/tomoyo/file.c:151 [inline] > tomoyo_path_perm+0x2b7/0x740 security/tomoyo/file.c:822 > security_inode_getattr+0x130/0x330 security/security.c:2371 > vfs_getattr+0x45/0x430 fs/stat.c:204 > vfs_fstat fs/stat.c:229 [inline] > vfs_fstatat+0xe4/0x190 fs/stat.c:338 > __do_sys_newfstatat fs/stat.c:505 [inline] > __se_sys_newfstatat fs/stat.c:499 [inline] > __x64_sys_newfstatat+0x11d/0x1a0 fs/stat.c:499 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Memory state around the buggy address: > ffff888026399f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88802639a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >ffff88802639a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff88802639a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff88802639a180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > Tested on: > > commit: 8c245fe7 Merge tag 'net-6.12-rc2' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=13156307980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d0ca089c3fc6b54e > dashboard link: https://syzkaller.appspot.com/bug?extid=4c0d0c4cde787116d465 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > patch: https://syzkaller.appspot.com/x/patch.diff?x=17377580580000 > -- Luiz Augusto von Dentz
