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Groups > linux.kernel > #1551222

[PATCH 4.9 42/83] ext4: fix in-superblock mount options processing

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.9 42/83] ext4: fix in-superblock mount options processing
Date 2017-01-04 21:30 +0100
Message-ID <sW0m6-1bZ-25@gated-at.bofh.it> (permalink)
References <sW02J-12y-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

commit 5aee0f8a3f42c94c5012f1673420aee96315925a upstream.

Fix a large number of problems with how we handle mount options in the
superblock.  For one, if the string in the superblock is long enough
that it is not null terminated, we could run off the end of the string
and try to interpret superblocks fields as characters.  It's unlikely
this will cause a security problem, but it could result in an invalid
parse.  Also, parse_options is destructive to the string, so in some
cases if there is a comma-separated string, it would be modified in
the superblock.  (Fortunately it only happens on file systems with a
1k block size.)

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ext4/super.c |   38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3301,7 +3301,7 @@ static int ext4_fill_super(struct super_
 	char *orig_data = kstrdup(data, GFP_KERNEL);
 	struct buffer_head *bh;
 	struct ext4_super_block *es = NULL;
-	struct ext4_sb_info *sbi;
+	struct ext4_sb_info *sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 	ext4_fsblk_t block;
 	ext4_fsblk_t sb_block = get_sb_block(&data);
 	ext4_fsblk_t logical_sb_block;
@@ -3320,16 +3320,14 @@ static int ext4_fill_super(struct super_
 	unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
 	ext4_group_t first_not_zeroed;
 
-	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
-	if (!sbi)
-		goto out_free_orig;
+	if ((data && !orig_data) || !sbi)
+		goto out_free_base;
 
 	sbi->s_blockgroup_lock =
 		kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
-	if (!sbi->s_blockgroup_lock) {
-		kfree(sbi);
-		goto out_free_orig;
-	}
+	if (!sbi->s_blockgroup_lock)
+		goto out_free_base;
+
 	sb->s_fs_info = sbi;
 	sbi->s_sb = sb;
 	sbi->s_inode_readahead_blks = EXT4_DEF_INODE_READAHEAD_BLKS;
@@ -3475,11 +3473,19 @@ static int ext4_fill_super(struct super_
 	 */
 	sbi->s_li_wait_mult = EXT4_DEF_LI_WAIT_MULT;
 
-	if (!parse_options((char *) sbi->s_es->s_mount_opts, sb,
-			   &journal_devnum, &journal_ioprio, 0)) {
-		ext4_msg(sb, KERN_WARNING,
-			 "failed to parse options in superblock: %s",
-			 sbi->s_es->s_mount_opts);
+	if (sbi->s_es->s_mount_opts[0]) {
+		char *s_mount_opts = kstrndup(sbi->s_es->s_mount_opts,
+					      sizeof(sbi->s_es->s_mount_opts),
+					      GFP_KERNEL);
+		if (!s_mount_opts)
+			goto failed_mount;
+		if (!parse_options(s_mount_opts, sb, &journal_devnum,
+				   &journal_ioprio, 0)) {
+			ext4_msg(sb, KERN_WARNING,
+				 "failed to parse options in superblock: %s",
+				 s_mount_opts);
+		}
+		kfree(s_mount_opts);
 	}
 	sbi->s_def_mount_opt = sbi->s_mount_opt;
 	if (!parse_options((char *) data, sb, &journal_devnum,
@@ -4157,7 +4163,9 @@ no_journal:
 
 	if (___ratelimit(&ext4_mount_msg_ratelimit, "EXT4-fs mount"))
 		ext4_msg(sb, KERN_INFO, "mounted filesystem with%s. "
-			 "Opts: %s%s%s", descr, sbi->s_es->s_mount_opts,
+			 "Opts: %.*s%s%s", descr,
+			 (int) sizeof(sbi->s_es->s_mount_opts),
+			 sbi->s_es->s_mount_opts,
 			 *sbi->s_es->s_mount_opts ? "; " : "", orig_data);
 
 	if (es->s_error_count)
@@ -4236,8 +4244,8 @@ failed_mount:
 out_fail:
 	sb->s_fs_info = NULL;
 	kfree(sbi->s_blockgroup_lock);
+out_free_base:
 	kfree(sbi);
-out_free_orig:
 	kfree(orig_data);
 	return err ? err : ret;
 }

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[PATCH 4.9 00/83] 4.9.1-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:20 +0100
  [PATCH 4.9 68/83] CIFS: Fix a possible memory corruption during reconnect Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 26/83] ALSA: hda - Gate the mic jack on HP Z1 Gen3 AiO Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 33/83] mm: Add a user_ns owner to mm_struct and fix ptrace permission checks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 38/83] ext4: dont lock buffer in ext4_commit_super if holding spinlock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 39/83] ext4: fix mballoc breakage with 64k block size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 17/83] usb: gadget: f_uac2: fix error handling at afunc_bind Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 41/83] ext4: use more strict checks for inodes_per_block on mount Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 36/83] ptrace: Dont allow accessing an undumpable mm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 56/83] PM / OPP: Pass opp_table to dev_pm_opp_put_regulator() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 35/83] ptrace: Capture the ptracers creds not PT_PTRACE_CAP Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 42/83] ext4: fix in-superblock mount options processing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 40/83] ext4: fix stack memory corruption with 64k block size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 25/83] ALSA: hda - fix headset-mic problem on a Dell laptop Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 64/83] dm raid: fix discard support regression Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 31/83] splice: reinstate SIGPIPE/EPIPE handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 59/83] dm table: fix all_blk_mq inconsistency when an empty table is loaded Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 34/83] vfs,mm: fix return value of read() at s_maxbytes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 54/83] mm, page_alloc: keep pcp count and list contents in sync if struct page is corrupted Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 32/83] block_dev: dont test bdev->bd_contains when it is not stable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 13/83] USB: cdc-acm: add device id for GW Instek AFG-125 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 12/83] USB: serial: kl5kusb105: fix open error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 30/83] fs: exec: apply CLOEXEC before changing dumpable task flags Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 29/83] exec: Ensure mm->user_ns contains the execed files Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 62/83] dm crypt: mark key as invalid until properly loaded Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 28/83] clk: ti: omap36xx: Work around sprz319 advisory 2.1 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 66/83] ASoC: intel: Fix crash at suspend/resume without card registration Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 43/83] ext4: add sanity checking to count_overhead() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 55/83] usb: gadget: composite: always set ep->mult to a sensible value Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  [PATCH 4.9 58/83] blk-mq: Do not invoke .queue_rq() for a stopped queue Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 21:30 +0100
  Re: [PATCH 4.9 00/83] 4.9.1-stable review Shuah Khan <shuah.kh@samsung.com> - 2017-01-05 01:50 +0100
    Re: [PATCH 4.9 00/83] 4.9.1-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-05 09:00 +0100
  Re: [PATCH 4.9 00/83] 4.9.1-stable review Guenter Roeck <linux@roeck-us.net> - 2017-01-05 06:00 +0100
    Re: [PATCH 4.9 00/83] 4.9.1-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-05 09:00 +0100

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