================================================================== BUG: KASAN: use-after-free in atomic_dec_and_test include/asm-generic/atomic-instrumented.h:259 [inline] BUG: KASAN: use-after-free in ucma_put_ctx+0x1d/0x60 drivers/infiniband/core/ucma.c:160 Write of size 4 at addr ffff8801ce907e98 by task syz-executor2/11937 CPU: 1 PID: 11937 Comm: syz-executor2 Not tainted 4.19.0-rc4+ #249 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 atomic_dec_and_test include/asm-generic/atomic-instrumented.h:259 [inline] ucma_put_ctx+0x1d/0x60 drivers/infiniband/core/ucma.c:160 ucma_resolve_ip+0x24d/0x2a0 drivers/infiniband/core/ucma.c:715 ucma_write+0x336/0x420 drivers/infiniband/core/ucma.c:1686 __vfs_write+0x119/0x9f0 fs/read_write.c:485 vfs_write+0x1fc/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457679 Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f053f857c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f053f8586d4 RCX: 0000000000457679 RDX: 0000000000000048 RSI: 0000000020000240 RDI: 0000000000000005 RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d8a48 R14: 00000000004cb698 R15: 0000000000000001 Allocated by task 11937: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620 kmalloc include/linux/slab.h:513 [inline] kzalloc include/linux/slab.h:707 [inline] ucma_alloc_ctx+0xce/0x690 drivers/infiniband/core/ucma.c:207 ucma_create_id+0x27d/0x990 drivers/infiniband/core/ucma.c:498 ucma_write+0x336/0x420 drivers/infiniband/core/ucma.c:1686 __vfs_write+0x119/0x9f0 fs/read_write.c:485 vfs_write+0x1fc/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 11930: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3813 ucma_free_ctx+0x9e6/0xdb0 drivers/infiniband/core/ucma.c:597 ucma_close+0x10d/0x300 drivers/infiniband/core/ucma.c:1770 __fput+0x385/0xa30 fs/file_table.c:278 ____fput+0x15/0x20 fs/file_table.c:309 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8801ce907e40 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 88 bytes inside of 256-byte region [ffff8801ce907e40, ffff8801ce907f40) The buggy address belongs to the page: page:ffffea00073a41c0 count:1 mapcount:0 mapping:ffff8801da8007c0 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea00073bdc48 ffffea0006dfef48 ffff8801da8007c0 raw: 0000000000000000 ffff8801ce907080 000000010000000c 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801ce907d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801ce907e00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb >ffff8801ce907e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801ce907f00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff8801ce907f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================