diff options
author | Al Viro <viro@zeniv.linux.org.uk> | 2023-09-19 22:53:32 +0300 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2024-02-25 10:10:31 +0300 |
commit | a13d1a4de3b0fe3c41d818697d691c886c5585fa (patch) | |
tree | 11151a4b7d601adc3841c7d1ecb6f3d53f1aa932 | |
parent | 529f89a9e4531e80c44871d7d0c30df6540c20e5 (diff) | |
download | linux-a13d1a4de3b0fe3c41d818697d691c886c5585fa.tar.xz |
exfat: move freeing sbi, upcase table and dropping nls into rcu-delayed helper
That stuff can be accessed by ->d_hash()/->d_compare(); as it is, we have
a hard-to-hit UAF if rcu pathwalk manages to get into ->d_hash() on a filesystem
that is in process of getting shut down.
Besides, having nls and upcase table cleanup moved from ->put_super() towards
the place where sbi is freed makes for simpler failure exits.
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r-- | fs/exfat/exfat_fs.h | 1 | ||||
-rw-r--r-- | fs/exfat/nls.c | 14 | ||||
-rw-r--r-- | fs/exfat/super.c | 20 |
3 files changed, 16 insertions, 19 deletions
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h index 9474cd50da6d..361595433480 100644 --- a/fs/exfat/exfat_fs.h +++ b/fs/exfat/exfat_fs.h @@ -275,6 +275,7 @@ struct exfat_sb_info { spinlock_t inode_hash_lock; struct hlist_head inode_hashtable[EXFAT_HASH_SIZE]; + struct rcu_head rcu; }; #define EXFAT_CACHE_VALID 0 diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c index 705710f93e2d..afdf13c34ff5 100644 --- a/fs/exfat/nls.c +++ b/fs/exfat/nls.c @@ -655,7 +655,6 @@ static int exfat_load_upcase_table(struct super_block *sb, unsigned int sect_size = sb->s_blocksize; unsigned int i, index = 0; u32 chksum = 0; - int ret; unsigned char skip = false; unsigned short *upcase_table; @@ -673,8 +672,7 @@ static int exfat_load_upcase_table(struct super_block *sb, if (!bh) { exfat_err(sb, "failed to read sector(0x%llx)", (unsigned long long)sector); - ret = -EIO; - goto free_table; + return -EIO; } sector++; for (i = 0; i < sect_size && index <= 0xFFFF; i += 2) { @@ -701,15 +699,12 @@ static int exfat_load_upcase_table(struct super_block *sb, exfat_err(sb, "failed to load upcase table (idx : 0x%08x, chksum : 0x%08x, utbl_chksum : 0x%08x)", index, chksum, utbl_checksum); - ret = -EINVAL; -free_table: - exfat_free_upcase_table(sbi); - return ret; + return -EINVAL; } static int exfat_load_default_upcase_table(struct super_block *sb) { - int i, ret = -EIO; + int i; struct exfat_sb_info *sbi = EXFAT_SB(sb); unsigned char skip = false; unsigned short uni = 0, *upcase_table; @@ -740,8 +735,7 @@ static int exfat_load_default_upcase_table(struct super_block *sb) return 0; /* FATAL error: default upcase table has error */ - exfat_free_upcase_table(sbi); - return ret; + return -EIO; } int exfat_create_upcase_table(struct super_block *sb) diff --git a/fs/exfat/super.c b/fs/exfat/super.c index d9d4fa91010b..fcb658267765 100644 --- a/fs/exfat/super.c +++ b/fs/exfat/super.c @@ -39,9 +39,6 @@ static void exfat_put_super(struct super_block *sb) exfat_free_bitmap(sbi); brelse(sbi->boot_bh); mutex_unlock(&sbi->s_lock); - - unload_nls(sbi->nls_io); - exfat_free_upcase_table(sbi); } static int exfat_sync_fs(struct super_block *sb, int wait) @@ -600,7 +597,7 @@ static int __exfat_fill_super(struct super_block *sb) ret = exfat_load_bitmap(sb); if (ret) { exfat_err(sb, "failed to load alloc-bitmap"); - goto free_upcase_table; + goto free_bh; } ret = exfat_count_used_clusters(sb, &sbi->used_clusters); @@ -613,8 +610,6 @@ static int __exfat_fill_super(struct super_block *sb) free_alloc_bitmap: exfat_free_bitmap(sbi); -free_upcase_table: - exfat_free_upcase_table(sbi); free_bh: brelse(sbi->boot_bh); return ret; @@ -701,12 +696,10 @@ put_inode: sb->s_root = NULL; free_table: - exfat_free_upcase_table(sbi); exfat_free_bitmap(sbi); brelse(sbi->boot_bh); check_nls_io: - unload_nls(sbi->nls_io); return err; } @@ -771,13 +764,22 @@ static int exfat_init_fs_context(struct fs_context *fc) return 0; } +static void delayed_free(struct rcu_head *p) +{ + struct exfat_sb_info *sbi = container_of(p, struct exfat_sb_info, rcu); + + unload_nls(sbi->nls_io); + exfat_free_upcase_table(sbi); + exfat_free_sbi(sbi); +} + static void exfat_kill_sb(struct super_block *sb) { struct exfat_sb_info *sbi = sb->s_fs_info; kill_block_super(sb); if (sbi) - exfat_free_sbi(sbi); + call_rcu(&sbi->rcu, delayed_free); } static struct file_system_type exfat_fs_type = { |