[v6.6] KASAN: slab-use-after-free Read in txAllocPMap

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: da47cbc25466 Linux 6.6.144
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16382b39580000
kernel config: https://syzkaller.appspot.com/x/.config?x=938110aa66424b94
dashboard link: https://syzkaller.appspot.com/bug?extid=f653cca4d1c46fdecd9e
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a9e82134d7e6/disk-da47cbc2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/296a86743157/vmlinux-da47cbc2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c5adb532f254/bzImage-da47cbc2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f653cc...@syzkaller.appspotmail.com

ERROR: (device loop3): dbUpdatePMap: blocks are outside the map
blkno = 6161616161, nblocks = 616161
ERROR: (device loop3): dbUpdatePMap: blocks are outside the map
blkno = 6c00003065, nblocks = 69662f
ERROR: (device loop3): dbUpdatePMap: blocks are outside the map
==================================================================
BUG: KASAN: slab-use-after-free in txAllocPMap+0x47f/0x6b0 fs/jfs/jfs_txnmgr.c:2412
Read of size 1 at addr ffff88805d465000 by task jfsCommit/114

CPU: 0 PID: 114 Comm: jfsCommit Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
<TASK>
dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xa8/0x210 mm/kasan/report.c:468
kasan_report+0x117/0x150 mm/kasan/report.c:581
txAllocPMap+0x47f/0x6b0 fs/jfs/jfs_txnmgr.c:2412
txUpdateMap+0x2b7/0x8b0 fs/jfs/jfs_txnmgr.c:2309
txLazyCommit fs/jfs/jfs_txnmgr.c:2665 [inline]
jfs_lazycommit+0x439/0xaa0 fs/jfs/jfs_txnmgr.c:2733
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>

Allocated by task 49:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
kmem_cache_alloc_node+0x1af/0x310 mm/slub.c:3540
__alloc_skb+0x103/0x2c0 net/core/skbuff.c:643
alloc_skb include/linux/skbuff.h:1316 [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+0x253/0xa90 drivers/net/netdevsim/dev.c:851
process_one_work kernel/workqueue.c:2653 [inline]
process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730
worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Freed by task 49:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1811 [inline]
slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
slab_free mm/slub.c:3830 [inline]
kmem_cache_free+0xf8/0x290 mm/slub.c:3852
nsim_dev_trap_report drivers/net/netdevsim/dev.c:821 [inline]
nsim_dev_trap_report_work+0x723/0xa90 drivers/net/netdevsim/dev.c:851
process_one_work kernel/workqueue.c:2653 [inline]
process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730
worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

The buggy address belongs to the object at ffff88805d465000
which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 0 bytes inside of
freed 240-byte region [ffff88805d465000, ffff88805d4650f0)

The buggy address belongs to the physical page:
page:ffffea0001751940 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5d465
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888141a65640 ffffea0001751900 0000000000000006
raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY), pid 3485, tgid 3485 (kworker/u4:10), ts 85547291107, free_ts 29734613213
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
prep_new_page mm/page_alloc.c:1589 [inline]
get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
__alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
alloc_slab_page+0x5d/0x180 mm/slub.c:1881
allocate_slab mm/slub.c:2028 [inline]
new_slab+0x87/0x2d0 mm/slub.c:2081
___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253
__slab_alloc mm/slub.c:3339 [inline]
__slab_alloc_node mm/slub.c:3392 [inline]
slab_alloc_node mm/slub.c:3485 [inline]
kmem_cache_alloc_node+0x12e/0x310 mm/slub.c:3540
__alloc_skb+0x103/0x2c0 net/core/skbuff.c:643
alloc_skb include/linux/skbuff.h:1316 [inline]
nlmsg_new include/net/netlink.h:1010 [inline]
inet6_rt_notify+0xb4/0x240 net/ipv6/route.c:6250
fib6_add_rt2node net/ipv6/ip6_fib.c:1274 [inline]
fib6_add+0x1e1a/0x49d0 net/ipv6/ip6_fib.c:1503
__ip6_ins_rt net/ipv6/route.c:1356 [inline]
ip6_ins_rt+0xd7/0x130 net/ipv6/route.c:1366
__ipv6_ifa_notify+0x662/0xb40 net/ipv6/addrconf.c:6279
ipv6_ifa_notify net/ipv6/addrconf.c:6318 [inline]
addrconf_dad_completed+0x1a2/0xd90 net/ipv6/addrconf.c:4307
addrconf_dad_work+0xc9e/0x1550 net/ipv6/addrconf.c:-1
process_one_work kernel/workqueue.c:2653 [inline]
process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730
worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1182 [inline]
free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
free_contig_range+0xa1/0x150 mm/page_alloc.c:6421
destroy_args+0x7d/0x840 mm/debug_vm_pgtable.c:1015
debug_vm_pgtable+0x411/0x440 mm/debug_vm_pgtable.c:1400
do_one_initcall+0x242/0x790 init/main.c:1249
do_initcall_level+0x13d/0x1f0 init/main.c:1311
do_initcalls+0x69/0xd0 init/main.c:1327
kernel_init_freeable+0x3d9/0x560 init/main.c:1564
kernel_init+0x1d/0x1c0 init/main.c:1454
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Memory state around the buggy address:
ffff88805d464f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88805d464f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805d465000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88805d465080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
ffff88805d465100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
==================================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: da47cbc25466 Linux 6.6.144
git tree: linux-6.6.y

console output: https://syzkaller.appspot.com/x/log.txt?x=17756b39580000

kernel config: https://syzkaller.appspot.com/x/.config?x=938110aa66424b94
dashboard link: https://syzkaller.appspot.com/bug?extid=f653cca4d1c46fdecd9e
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16b12589580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17ecf546580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a9e82134d7e6/disk-da47cbc2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/296a86743157/vmlinux-da47cbc2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c5adb532f254/bzImage-da47cbc2.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/6155abd1d9f6/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=171e0739580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f653cc...@syzkaller.appspotmail.com

ERROR: (device loop0): dbUpdatePMap: blocks are outside the map

blkno = 6161616161, nblocks = 616161

ERROR: (device loop0): dbUpdatePMap: blocks are outside the map

blkno = 6c00003065, nblocks = 69662f

ERROR: (device loop0): dbUpdatePMap: blocks are outside the map
==================================================================
BUG: KASAN: use-after-free in txAllocPMap+0x47f/0x6b0 fs/jfs/jfs_txnmgr.c:2412
Read of size 1 at addr ffff88802f61c000 by task jfsCommit/111

CPU: 1 PID: 111 Comm: jfsCommit Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
<TASK>
dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xa8/0x210 mm/kasan/report.c:468
kasan_report+0x117/0x150 mm/kasan/report.c:581
txAllocPMap+0x47f/0x6b0 fs/jfs/jfs_txnmgr.c:2412
txUpdateMap+0x2b7/0x8b0 fs/jfs/jfs_txnmgr.c:2309
txLazyCommit fs/jfs/jfs_txnmgr.c:2665 [inline]
jfs_lazycommit+0x439/0xaa0 fs/jfs/jfs_txnmgr.c:2733
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>

The buggy address belongs to the physical page:

page:ffffea0000bd8700 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2f61c
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffff7f(buddy)
raw: 00fff00000000000 ffffea0001dd5788 ffffea0001d44b88 0000000000000000
raw: 0000000000000000 0000000000000001 00000000ffffff7f 0000000000000000

page dumped because: kasan: bad access detected

page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x540dc0(GFP_USER|__GFP_COMP|__GFP_ZERO|__GFP_ACCOUNT), pid 5911, tgid 5911 (sed), ts 87798904584, free_ts 87818794900

set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
prep_new_page mm/page_alloc.c:1589 [inline]
get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
__alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501

pagetable_alloc include/linux/mm.h:2900 [inline]
__pte_alloc_one include/asm-generic/pgalloc.h:68 [inline]
pte_alloc_one+0x84/0x540 arch/x86/mm/pgtable.c:33
__do_fault+0xd7/0x4d0 mm/memory.c:4239
do_cow_fault mm/memory.c:4674 [inline]
do_fault mm/memory.c:4777 [inline]
do_pte_missing mm/memory.c:3689 [inline]
handle_pte_fault mm/memory.c:5047 [inline]
__handle_mm_fault mm/memory.c:5188 [inline]
handle_mm_fault+0x2c86/0x4a50 mm/memory.c:5353
do_user_addr_fault+0x736/0x12d0 arch/x86/mm/fault.c:1371
handle_page_fault arch/x86/mm/fault.c:1463 [inline]
exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608

page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1182 [inline]
free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366

free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2505
release_pages+0x208a/0x2300 mm/swap.c:1022
tlb_batch_pages_flush mm/mmu_gather.c:99 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:294 [inline]
tlb_flush_mmu+0x379/0x510 mm/mmu_gather.c:301
tlb_finish_mmu+0xf4/0x220 mm/mmu_gather.c:425
exit_mmap+0x428/0xb90 mm/mmap.c:3315
__mmput+0x118/0x3a0 kernel/fork.c:1357
exit_mm+0x23f/0x340 kernel/exit.c:570
do_exit+0x909/0x2530 kernel/exit.c:871
do_group_exit+0x22d/0x2f0 kernel/exit.c:1026
__do_sys_exit_group kernel/exit.c:1037 [inline]
__se_sys_exit_group kernel/exit.c:1035 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1035
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:

ffff88802f61bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88802f61bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88802f61c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88802f61c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88802f61c100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
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