CVE-2025-38194

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

jffs2: check that raw node were preallocated before writing summary

Syzkaller detected a kernel bug in jffs2linknoderef, caused by fault injection in jffs2preallocrawnoderefs. jffs2sumwritesumnode doesn't check return value of jffs2preallocrawnoderefs and simply lets any error propagate into jffs2sumwritedata, which eventually calls jffs2linknoderef in order to link the summary to an expectedly allocated node.

kernel BUG at fs/jffs2/nodelist.c:592! invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 1 PID: 31277 Comm: syz-executor.7 Not tainted 6.1.128-syzkaller-00139-ge10f83ca10a1 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:jffs2linknoderef+0x570/0x690 fs/jffs2/nodelist.c:592 Call Trace: <TASK> jffs2sumwritedata fs/jffs2/summary.c:841 [inline] jffs2sumwritesumnode+0xd1a/0x1da0 fs/jffs2/summary.c:874 jffs2doreservespace+0xa18/0xd60 fs/jffs2/nodemgmt.c:388 jffs2reservespace+0x55f/0xaa0 fs/jffs2/nodemgmt.c:197 jffs2writeinoderange+0x246/0xb50 fs/jffs2/write.c:362 jffs2writeend+0x726/0x15d0 fs/jffs2/file.c:301 genericperform_write+0x314/0x5d0 mm/filemap.c:3856 __genericfilewriteiter+0x2ae/0x4d0 mm/filemap.c:3973 genericfilewriteiter+0xe3/0x350 mm/filemap.c:4005 callwriteiter include/linux/fs.h:2265 [inline] doiterreadvwritev+0x20f/0x3c0 fs/readwrite.c:735 doiterwrite+0x186/0x710 fs/readwrite.c:861 vfsiterwrite+0x70/0xa0 fs/readwrite.c:902 iterfilesplicewrite+0x73b/0xc90 fs/splice.c:685 dosplicefrom fs/splice.c:763 [inline] directspliceactor+0x10c/0x170 fs/splice.c:950 splicedirecttoactor+0x337/0xa10 fs/splice.c:896 dosplicedirect+0x1a9/0x280 fs/splice.c:1002 dosendfile+0xb13/0x12c0 fs/readwrite.c:1255 __dosyssendfile64 fs/read_write.c:1323 [inline] __sesyssendfile64 fs/read_write.c:1309 [inline] _x64syssendfile64+0x1cf/0x210 fs/readwrite.c:1309 dosyscallx64 arch/x86/entry/common.c:51 [inline] dosyscall64+0x35/0x80 arch/x86/entry/common.c:81 entrySYSCALL64afterhwframe+0x6e/0xd8

Fix this issue by checking return value of jffs2preallocrawnoderefs before calling jffs2sumwrite_data.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.