From db42549d402cb44fe67c95d08f1a9ea902d32e7e Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Sat, 4 May 2024 13:26:37 -0400
Subject: [PATCH] bcachefs: Add a better limit for maximum number of buckets
The bucket_gens array is a single array allocation (one byte per
bucket), and kernel allocations are still limited to INT_MAX.
Check this limit to avoid failing the bucket_gens array allocation.
Reported-by: syzbot+b29f436493184ea42e2b@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/bcachefs/bcachefs_format.h | 6 ++++++
fs/bcachefs/errcode.h | 1 +
fs/bcachefs/sb-members.c | 6 +++---
fs/bcachefs/super.c | 7 +++++++
4 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
index f7fbfccd2b1e4..8345a2b2d05be 100644
--- a/fs/bcachefs/bcachefs_format.h
+++ b/fs/bcachefs/bcachefs_format.h
@@ -591,6 +591,12 @@ struct bch_member {
__le64 btree_allocated_bitmap;
};
+/*
+ * This limit comes from the bucket_gens array - it's a single allocation, and
+ * kernel allocation are limited to INT_MAX
+ */
+#define BCH_MEMBER_NBUCKETS_MAX (INT_MAX - 64)
+
#define BCH_MEMBER_V1_BYTES 56
LE64_BITMASK(BCH_MEMBER_STATE, struct bch_member, flags, 0, 4)
diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
index 01a79fa3eacb2..dbe35b80bc0b8 100644
--- a/fs/bcachefs/errcode.h
+++ b/fs/bcachefs/errcode.h
@@ -175,6 +175,7 @@
x(EINVAL, block_size_too_small) \
x(EINVAL, bucket_size_too_small) \
x(EINVAL, device_size_too_small) \
+ x(EINVAL, device_size_too_big) \
x(EINVAL, device_not_a_member_of_filesystem) \
x(EINVAL, device_has_been_removed) \
x(EINVAL, device_splitbrain) \
diff --git a/fs/bcachefs/sb-members.c b/fs/bcachefs/sb-members.c
index 5b8e621ac5eb5..44b3f0cb7b497 100644
--- a/fs/bcachefs/sb-members.c
+++ b/fs/bcachefs/sb-members.c
@@ -124,9 +124,9 @@ static int validate_member(struct printbuf *err,
struct bch_sb *sb,
int i)
{
- if (le64_to_cpu(m.nbuckets) > LONG_MAX) {
- prt_printf(err, "device %u: too many buckets (got %llu, max %lu)",
- i, le64_to_cpu(m.nbuckets), LONG_MAX);
+ if (le64_to_cpu(m.nbuckets) > BCH_MEMBER_NBUCKETS_MAX) {
+ prt_printf(err, "device %u: too many buckets (got %llu, max %u)",
+ i, le64_to_cpu(m.nbuckets), BCH_MEMBER_NBUCKETS_MAX);
return -BCH_ERR_invalid_sb_members;
}
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index c2c80e6890aee..dddf57ec4511f 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1959,6 +1959,13 @@ int bch2_dev_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
goto err;
}
+ if (nbuckets > BCH_MEMBER_NBUCKETS_MAX) {
+ bch_err(ca, "New device size too big (%llu greater than max %u)",
+ nbuckets, BCH_MEMBER_NBUCKETS_MAX);
+ ret = -BCH_ERR_device_size_too_big;
+ goto err;
+ }
+
if (bch2_dev_is_online(ca) &&
get_capacity(ca->disk_sb.bdev->bd_disk) <
ca->mi.bucket_size * nbuckets) {
--
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