The patch titled
Subject: nilfs2: fix shift-out-of-bounds due to too large exponent of block size
has been added to the -mm mm-nonmm-unstable branch. Its filename is
nilfs2-fix-shift-out-of-bounds-due-to-too-large-exponent-of-block-size.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/nilfs2-fix-shift-out-of-bounds-due-to-too-large-exponent-of-block-size.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Subject: nilfs2: fix shift-out-of-bounds due to too large exponent of block size
Date: Thu, 27 Oct 2022 13:43:06 +0900
If field s_log_block_size of superblock data is corrupted and too large,
init_nilfs() and load_nilfs() still can trigger a shift-out-of-bounds
warning followed by a kernel panic (if panic_on_warn is set):
shift exponent 38973 is too large for 32-bit type 'int'
Call Trace:
<TASK>
dump_stack_lvl+0xcd/0x134
ubsan_epilogue+0xb/0x50
__ubsan_handle_shift_out_of_bounds.cold.12+0x17b/0x1f5
init_nilfs.cold.11+0x18/0x1d [nilfs2]
nilfs_mount+0x9b5/0x12b0 [nilfs2]
...
This fixes the issue by adding and using a new helper function for getting
block size with sanity check.
Link: https://lkml.kernel.org/r/20221027044306.42774-3-konishi.ryusuke@xxxxxxxxx
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Tested-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/fs/nilfs2/the_nilfs.c~nilfs2-fix-shift-out-of-bounds-due-to-too-large-exponent-of-block-size
+++ a/fs/nilfs2/the_nilfs.c
@@ -194,6 +194,34 @@ static int nilfs_store_log_cursor(struct
}
/**
+ * nilfs_get_blocksize - get block size from raw superblock data
+ * @sb: super block instance
+ * @sbp: superblock raw data buffer
+ * @blocksize: place to store block size
+ *
+ * nilfs_get_blocksize() calculates the block size from the block size
+ * exponent information written in @sbp and stores it in @blocksize,
+ * or aborts with an error message if it's too large.
+ *
+ * Return Value: On success, 0 is returned. If the block size is too
+ * large, -EINVAL is returned.
+ */
+static int nilfs_get_blocksize(struct super_block *sb,
+ struct nilfs_super_block *sbp, int *blocksize)
+{
+ unsigned int shift_bits = le32_to_cpu(sbp->s_log_block_size);
+
+ if (unlikely(shift_bits >
+ ilog2(NILFS_MAX_BLOCK_SIZE) - BLOCK_SIZE_BITS)) {
+ nilfs_err(sb, "too large filesystem blocksize: 2 ^ %u KiB",
+ shift_bits);
+ return -EINVAL;
+ }
+ *blocksize = BLOCK_SIZE << shift_bits;
+ return 0;
+}
+
+/**
* load_nilfs - load and recover the nilfs
* @nilfs: the_nilfs structure to be released
* @sb: super block instance used to recover past segment
@@ -246,11 +274,15 @@ int load_nilfs(struct the_nilfs *nilfs,
nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
/* verify consistency between two super blocks */
- blocksize = BLOCK_SIZE << le32_to_cpu(sbp[0]->s_log_block_size);
+ err = nilfs_get_blocksize(sb, sbp[0], &blocksize);
+ if (err)
+ goto scan_error;
+
if (blocksize != nilfs->ns_blocksize) {
nilfs_warn(sb,
"blocksize differs between two super blocks (%d != %d)",
blocksize, nilfs->ns_blocksize);
+ err = -EINVAL;
goto scan_error;
}
@@ -609,9 +641,11 @@ int init_nilfs(struct the_nilfs *nilfs,
if (err)
goto failed_sbh;
- blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
- if (blocksize < NILFS_MIN_BLOCK_SIZE ||
- blocksize > NILFS_MAX_BLOCK_SIZE) {
+ err = nilfs_get_blocksize(sb, sbp, &blocksize);
+ if (err)
+ goto failed_sbh;
+
+ if (blocksize < NILFS_MIN_BLOCK_SIZE) {
nilfs_err(sb,
"couldn't mount because of unsupported filesystem blocksize %d",
blocksize);
_
Patches currently in -mm which might be from konishi.ryusuke@xxxxxxxxx are
nilfs2-fix-shift-out-of-bounds-overflow-in-nilfs_sb2_bad_offset.patch
nilfs2-fix-shift-out-of-bounds-due-to-too-large-exponent-of-block-size.patch
