bisecting fixing commit since f8ad8187c3b536ee2b10502a8340c014204a1af0
building syzkaller on 52e3731913ab2677be27c29ed8142b04e8f28521
testing commit f8ad8187c3b536ee2b10502a8340c014204a1af0 with gcc (GCC) 10.2.1 20210217
kernel signature: 1ae4ca6c61b7517e1ab76ca2845f8b8eeb14eed2597d2acd10ce9ac3edf5a682
run #0: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #1: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #2: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #3: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #4: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #5: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #6: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #7: crashed: KASAN: out-of-bounds Read in ext4_xattr_set_entry
run #8: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #9: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #10: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #11: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #12: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #13: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #14: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #15: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #16: OK
run #17: OK
run #18: OK
run #19: OK
testing current HEAD f69d02e37a85645aa90d18cacfff36dba370f797
testing commit f69d02e37a85645aa90d18cacfff36dba370f797 with gcc (GCC) 10.2.1 20210217
kernel signature: 3a2748c1ae197a625094e128c8de351510e1536f8a6cd91bba1bb38f9ca552ba
run #0: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #1: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #2: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #3: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #4: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #5: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #6: crashed: KASAN: use-after-free Read in ext4_xattr_set_entry
run #7: OK
run #8: OK
run #9: OK
revisions tested: 2, total time: 34m59.051711972s (build: 11m21.113615023s, test: 23m9.961975925s)
the crash still happens on HEAD
commit msg: Merge tag 'misc-5.12-2021-03-02' of git://git.kernel.dk/linux-block
crash: KASAN: use-after-free Read in ext4_xattr_set_entry
==================================================================
BUG: KASAN: use-after-free in ext4_xattr_set_entry+0xc14/0x3680 fs/ext4/xattr.c:1586
Read of size 4 at addr ffff88802d96e004 by task syz-executor.0/600

CPU: 0 PID: 600 Comm: syz-executor.0 Not tainted 5.12.0-rc1-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+0x93/0xc2 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
 __kasan_report mm/kasan/report.c:399 [inline]
 kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
 ext4_xattr_set_entry+0xc14/0x3680 fs/ext4/xattr.c:1586
 ext4_xattr_ibody_set+0x60/0x260 fs/ext4/xattr.c:2224
 ext4_xattr_set_handle+0x6da/0x1080 fs/ext4/xattr.c:2380
 ext4_xattr_set+0x11d/0x2c0 fs/ext4/xattr.c:2493
 __vfs_setxattr+0xdb/0x130 fs/xattr.c:180
 __vfs_setxattr_noperm+0xee/0x480 fs/xattr.c:214
 vfs_setxattr+0x111/0x2d0 fs/xattr.c:300
 setxattr+0x157/0x260 fs/xattr.c:573
 path_setxattr+0x13c/0x170 fs/xattr.c:593
 __do_sys_setxattr fs/xattr.c:609 [inline]
 __se_sys_setxattr fs/xattr.c:605 [inline]
 __x64_sys_setxattr+0xbb/0x150 fs/xattr.c:605
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x465b09
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:00007f67264e5188 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465b09
RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000020000100
RBP: 00000000004b069f R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007fff04069c4f R14: 00007f67264e5300 R15: 0000000000022000

The buggy address belongs to the page:
page:0000000005ae736f refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x2d96e
flags: 0xfff00000000000()
raw: 00fff00000000000 ffffea0000b5f2c8 ffffea0000b65bc8 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88802d96df00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88802d96df80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88802d96e000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88802d96e080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88802d96e100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================