Syzkaller detected a kernel bug in jffs2_link_node_ref, caused by fault injection in jffs2_prealloc_raw_node_refs. jffs2_sum_write_sumnode doesn't check return value of jffs2_prealloc_raw_node_refs and simply lets any error propagate into jffs2_sum_write_data, which eventually calls jffs2_link_node_ref 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:jffs2_link_node_ref+0x570/0x690 fs/jffs2/nodelist.c:592 Call Trace: <TASK> jffs2_sum_write_data fs/jffs2/summary.c:841 [inline] jffs2_sum_write_sumnode+0xd1a/0x1da0 fs/jffs2/summary.c:874 jffs2_do_reserve_space+0xa18/0xd60 fs/jffs2/nodemgmt.c:388 jffs2_reserve_space+0x55f/0xaa0 fs/jffs2/nodemgmt.c:197 jffs2_write_inode_range+0x246/0xb50 fs/jffs2/write.c:362 jffs2_write_end+0x726/0x15d0 fs/jffs2/file.c:301 generic_perform_write+0x314/0x5d0 mm/filemap.c:3856 __generic_file_write_iter+0x2ae/0x4d0 mm/filemap.c:3973 generic_file_write_iter+0xe3/0x350 mm/filemap.c:4005 call_write_iter include/linux/fs.h:2265 [inline] do_iter_readv_writev+0x20f/0x3c0 fs/read_write.c:735 do_iter_write+0x186/0x710 fs/read_write.c:861 vfs_iter_write+0x70/0xa0 fs/read_write.c:902 iter_file_splice_write+0x73b/0xc90 fs/splice.c:685 do_splice_from fs/splice.c:763 [inline] direct_splice_actor+0x10c/0x170 fs/splice.c:950 splice_direct_to_actor+0x337/0xa10 fs/splice.c:896 do_splice_direct+0x1a9/0x280 fs/splice.c:1002 do_sendfile+0xb13/0x12c0 fs/read_write.c:1255 __do_sys_sendfile64 fs/read_write.c:1323 [inline] __se_sys_sendfile64 fs/read_write.c:1309 [inline] __x64_sys_sendfile64+0x1cf/0x210 fs/read_write.c:1309 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8
Fix this issue by checking return value of jffs2_prealloc_raw_node_refs before calling jffs2_sum_write_data.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Cc: stable@vger.kernel.org Fixes: 2f785402f39b ("[JFFS2] Reduce visibility of raw_node_ref to upper layers of JFFS2 code.") Signed-off-by: Artem Sadovnikov a.sadovnikov@ispras.ru --- fs/jffs2/summary.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/jffs2/summary.c b/fs/jffs2/summary.c index 4fe64519870f1..d83372d3e1a07 100644 --- a/fs/jffs2/summary.c +++ b/fs/jffs2/summary.c @@ -858,7 +858,10 @@ int jffs2_sum_write_sumnode(struct jffs2_sb_info *c) spin_unlock(&c->erase_completion_lock);
jeb = c->nextblock; - jffs2_prealloc_raw_node_refs(c, jeb, 1); + ret = jffs2_prealloc_raw_node_refs(c, jeb, 1); + + if (ret) + goto out;
if (!c->summary->sum_num || !c->summary->sum_list_head) { JFFS2_WARNING("Empty summary info!!!\n"); @@ -872,6 +875,8 @@ int jffs2_sum_write_sumnode(struct jffs2_sb_info *c) datasize += padsize;
ret = jffs2_sum_write_data(c, jeb, infosize, datasize, padsize); + +out: spin_lock(&c->erase_completion_lock); return ret; }