CVE-2025-68796

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

f2fs: fix to avoid updating zero-sized extent in extent cache

As syzbot reported:

F2FS-fs (loop0): __updateextenttreerange: extent len is zero, type: 0, extent [0, 0, 0], age [0, 0] ------------[ cut here ]------------ kernel BUG at fs/f2fs/extentcache.c:678! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 5336 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:__updateextenttreerange+0x13bc/0x1500 fs/f2fs/extentcache.c:678 Call Trace: <TASK> f2fsupdatereadextentcacherange+0x192/0x3e0 fs/f2fs/extentcache.c:1085 f2fsdozerorange fs/f2fs/file.c:1657 [inline] f2fszerorange+0x10c1/0x1580 fs/f2fs/file.c:1737 f2fsfallocate+0x583/0x990 fs/f2fs/file.c:2030 vfsfallocate+0x669/0x7e0 fs/open.c:342 ioctlpreallocate fs/ioctl.c:289 [inline] fileioctl+0x611/0x780 fs/ioctl.c:-1 dovfs_ioctl+0xb33/0x1430 fs/ioctl.c:576 __dosysioctl fs/ioctl.c:595 [inline] __sesysioctl+0x82/0x170 fs/ioctl.c:583 dosyscallx64 arch/x86/entry/syscall64.c:63 [inline] dosyscall64+0xfa/0x3b0 arch/x86/entry/syscall64.c:94 entrySYSCALL64afterhwframe+0x77/0x7f RIP: 0033:0x7f07bc58eec9

In error path of f2fszerorange(), it may add a zero-sized extent into extent cache, it should be avoided.