CVE-2025-37806

In the Linux kernel, the following vulnerability has been resolved:

fs/ntfs3: Keep write operations atomic

syzbot reported a NULL pointer dereference in __generic_file_write_iter. [1]

Before the write operation is completed, the user executes ioctl[2] to clear

the compress flag of the file, which causes the is_compressed() judgment to

return 0, further causing the program to enter the wrong process and call the

wrong ops ntfs_aops_cmpr, which triggers the null pointer dereference of

write_begin.

Use inode lock to synchronize ioctl and write to avoid this case.

[1]

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000

Mem abort info:

ESR = 0x0000000086000006

EC = 0x21: IABT (current EL), IL = 32 bits

SET = 0, FnV = 0

EA = 0, S1PTW = 0

FSC = 0x06: level 2 translation fault

user pgtable: 4k pages, 48-bit VAs, pgdp=000000011896d000

[0000000000000000] pgd=0800000118b44403, p4d=0800000118b44403, pud=0800000117517403, pmd=0000000000000000

Internal error: Oops: 0000000086000006 [#1] PREEMPT SMP

Modules linked in:

CPU: 0 UID: 0 PID: 6427 Comm: syz-executor347 Not tainted 6.13.0-rc3-syzkaller-g573067a5a685 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024

pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)

pc : 0x0

lr : generic_perform_write+0x29c/0x868 mm/filemap.c:4055

sp : ffff80009d4978a0

x29: ffff80009d4979c0 x28: dfff800000000000 x27: ffff80009d497bc8

x26: 0000000000000000 x25: ffff80009d497960 x24: ffff80008ba71c68

x23: 0000000000000000 x22: ffff0000c655dac0 x21: 0000000000001000

x20: 000000000000000c x19: 1ffff00013a92f2c x18: ffff0000e183aa1c

x17: 0004060000000014 x16: ffff800083275834 x15: 0000000000000001

x14: 0000000000000000 x13: 0000000000000001 x12: ffff0000c655dac0

x11: 0000000000ff0100 x10: 0000000000ff0100 x9 : 0000000000000000

x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000

x5 : ffff80009d497980 x4 : ffff80009d497960 x3 : 0000000000001000

x2 : 0000000000000000 x1 : ffff0000e183a928 x0 : ffff0000d60b0fc0

Call trace:

0x0 (P)

__generic_file_write_iter+0xfc/0x204 mm/filemap.c:4156

ntfs_file_write_iter+0x54c/0x630 fs/ntfs3/file.c:1267

new_sync_write fs/read_write.c:586 [inline]

vfs_write+0x920/0xcf4 fs/read_write.c:679

ksys_write+0x15c/0x26c fs/read_write.c:731

__do_sys_write fs/read_write.c:742 [inline]

__se_sys_write fs/read_write.c:739 [inline]

__arm64_sys_write+0x7c/0x90 fs/read_write.c:739

__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]

invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49

el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132

do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151

el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744

el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762

[2]

ioctl$FS_IOC_SETFLAGS(r0, 0x40086602, &(0x7f00000000c0)=0x20)