Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_stripe_to_text

[Zhao Mengmeng]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 1ec6d097897adiff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c
index 141a4c63142f..0801db97394e 100644
--- a/fs/bcachefs/ec.c
+++ b/fs/bcachefs/ec.c
@@ -113,6 +113,12 @@ int bch2_stripe_validate(struct bch_fs *c, struct bkey_s_c k,
 	const struct bch_stripe *s = bkey_s_c_to_stripe(k).v;
 	int ret = 0;
 
+	if (s->csum_granularity_bits >= 32) {
+		bch_err(c, "stripe csum gran bits too big (%u)",
+			s->csum_granularity_bits);
+		return -BCH_ERR_stripe_csum_granularity_bits_too_big;
+	}
+
 	bkey_fsck_err_on(bkey_eq(k.k->p, POS_MIN) ||
 			 bpos_gt(k.k->p, POS(0, U32_MAX)),
 			 c, stripe_pos_bad,
diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
index 742dcdd3e5d7..14ba6bc7a029 100644
--- a/fs/bcachefs/errcode.h
+++ b/fs/bcachefs/errcode.h
@@ -258,7 +258,8 @@
 	x(BCH_ERR_nopromote,		nopromote_no_writes)			\
 	x(BCH_ERR_nopromote,		nopromote_enomem)			\
 	x(0,				invalid_snapshot_node)			\
-	x(0,				option_needs_open_fs)
+	x(0,				option_needs_open_fs)			\
+	x(EINVAL,			stripe_csum_granularity_bits_too_big)
 
 enum bch_errcode {
 	BCH_ERR_START		= 2048,