From: ZhangPeng <zhangpeng362@xxxxxxxxxx> [ Upstream commit c53ed55cb275344086e32a7080a6b19cb183650b ] Syzbot reported a OOB Write bug: loop0: detected capacity change from 0 to 64 ================================================================== BUG: KASAN: slab-out-of-bounds in hfs_asc2mac+0x467/0x9a0 fs/hfs/trans.c:133 Write of size 1 at addr ffff88801848314e by task syz-executor391/3632 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 print_address_description+0x74/0x340 mm/kasan/report.c:284 print_report+0x107/0x1f0 mm/kasan/report.c:395 kasan_report+0xcd/0x100 mm/kasan/report.c:495 hfs_asc2mac+0x467/0x9a0 fs/hfs/trans.c:133 hfs_cat_build_key+0x92/0x170 fs/hfs/catalog.c:28 hfs_lookup+0x1ab/0x2c0 fs/hfs/dir.c:31 lookup_open fs/namei.c:3391 [inline] open_last_lookups fs/namei.c:3481 [inline] path_openat+0x10e6/0x2df0 fs/namei.c:3710 do_filp_open+0x264/0x4f0 fs/namei.c:3740 If in->len is much larger than HFS_NAMELEN(31) which is the maximum length of an HFS filename, a OOB write could occur in hfs_asc2mac(). In that case, when the dst reaches the boundary, the srclen is still greater than 0, which causes a OOB write. Fix this by adding a check on dstlen in while() before writing to dst address. Link: https://lkml.kernel.org/r/20221202030038.1391945-1-zhangpeng362@xxxxxxxxxx Fixes: 328b92278650 ("[PATCH] hfs: NLS support") Signed-off-by: ZhangPeng <zhangpeng362@xxxxxxxxxx> Reviewed-by: Viacheslav Dubeyko <slava@xxxxxxxxxxx> Reported-by: <syzbot+dc3b1cf9111ab5fe98e7@xxxxxxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/hfs/trans.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/hfs/trans.c b/fs/hfs/trans.c index 39f5e343bf4d..fdb0edb8a607 100644 --- a/fs/hfs/trans.c +++ b/fs/hfs/trans.c @@ -109,7 +109,7 @@ void hfs_asc2mac(struct super_block *sb, struct hfs_name *out, const struct qstr if (nls_io) { wchar_t ch; - while (srclen > 0) { + while (srclen > 0 && dstlen > 0) { size = nls_io->char2uni(src, srclen, &ch); if (size < 0) { ch = '?'; -- 2.35.1
