v1->v2:
Add CC-stable tag in first patch.
Rename check_free_block() -> check_dquot_block_header().
v2->v3:
Define do_check_range() completely in patch 1.
Move 'dqdh_entries' checking into check_dquot_block_header().
Do block checing later in find_next_id().
Zhihao Cheng (3):
quota: Check next/prev free block number after reading from quota file
quota: Replace all block number checking with helper function
quota: Add more checking after reading from quota file
fs/quota/quota_tree.c | 73 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 61 insertions(+), 12 deletions(-)
--
2.31.1
Cleanup all block checking places, replace them with helper function
do_check_range().
Signed-off-by: Zhihao Cheng <[email protected]>
---
fs/quota/quota_tree.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
index 7e65d67de9f3..0fa73ca28045 100644
--- a/fs/quota/quota_tree.c
+++ b/fs/quota/quota_tree.c
@@ -518,12 +518,10 @@ static int remove_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
goto out_buf;
}
newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
- if (newblk < QT_TREEOFF || newblk >= info->dqi_blocks) {
- quota_error(dquot->dq_sb, "Getting block too big (%u >= %u)",
- newblk, info->dqi_blocks);
- ret = -EUCLEAN;
+ ret = do_check_range(dquot->dq_sb, "block", newblk, QT_TREEOFF,
+ info->dqi_blocks - 1);
+ if (ret)
goto out_buf;
- }
if (depth == info->dqi_qtree_depth - 1) {
ret = free_dqentry(info, dquot, newblk);
@@ -624,12 +622,10 @@ static loff_t find_tree_dqentry(struct qtree_mem_dqinfo *info,
blk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
if (!blk) /* No reference? */
goto out_buf;
- if (blk < QT_TREEOFF || blk >= info->dqi_blocks) {
- quota_error(dquot->dq_sb, "Getting block too big (%u >= %u)",
- blk, info->dqi_blocks);
- ret = -EUCLEAN;
+ ret = do_check_range(dquot->dq_sb, "block", blk, QT_TREEOFF,
+ info->dqi_blocks - 1);
+ if (ret)
goto out_buf;
- }
if (depth < info->dqi_qtree_depth - 1)
ret = find_tree_dqentry(info, dquot, blk, depth+1);
--
2.31.1
Following process:
Init: v2_read_file_info: <3> dqi_free_blk 0 dqi_free_entry 5 dqi_blks 6
Step 1. chown bin f_a -> dquot_acquire -> v2_write_dquot:
qtree_write_dquot
do_insert_tree
find_free_dqentry
get_free_dqblk
write_blk(info->dqi_blocks) // info->dqi_blocks = 6, failure. The
content in physical block (corresponding to blk 6) is random.
Step 2. chown root f_a -> dquot_transfer -> dqput_all -> dqput ->
ext4_release_dquot -> v2_release_dquot -> qtree_delete_dquot:
dquot_release
remove_tree
free_dqentry
put_free_dqblk(6)
info->dqi_free_blk = blk // info->dqi_free_blk = 6
Step 3. drop cache (buffer head for block 6 is released)
Step 4. chown bin f_b -> dquot_acquire -> commit_dqblk -> v2_write_dquot:
qtree_write_dquot
do_insert_tree
find_free_dqentry
get_free_dqblk
dh = (struct qt_disk_dqdbheader *)buf
blk = info->dqi_free_blk // 6
ret = read_blk(info, blk, buf) // The content of buf is random
info->dqi_free_blk = le32_to_cpu(dh->dqdh_next_free) // random blk
Step 5. chown bin f_c -> notify_change -> ext4_setattr -> dquot_transfer:
dquot = dqget -> acquire_dquot -> ext4_acquire_dquot -> dquot_acquire ->
commit_dqblk -> v2_write_dquot -> dq_insert_tree:
do_insert_tree
find_free_dqentry
get_free_dqblk
blk = info->dqi_free_blk // If blk < 0 and blk is not an error
code, it will be returned as dquot
transfer_to[USRQUOTA] = dquot // A random negative value
__dquot_transfer(transfer_to)
dquot_add_inodes(transfer_to[cnt])
spin_lock(&dquot->dq_dqb_lock) // page fault
, which will lead to kernel page fault:
Quota error (device sda): qtree_write_dquot: Error -8000 occurred
while creating quota
BUG: unable to handle page fault for address: ffffffffffffe120
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
Oops: 0002 [#1] PREEMPT SMP
CPU: 0 PID: 5974 Comm: chown Not tainted 6.0.0-rc1-00004
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:_raw_spin_lock+0x3a/0x90
Call Trace:
dquot_add_inodes+0x28/0x270
__dquot_transfer+0x377/0x840
dquot_transfer+0xde/0x540
ext4_setattr+0x405/0x14d0
notify_change+0x68e/0x9f0
chown_common+0x300/0x430
__x64_sys_fchownat+0x29/0x40
In order to avoid accessing invalid quota memory address, this patch adds
block number checking of next/prev free block read from quota file.
Fetch a reproducer in [Link].
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216372
Fixes: 1da177e4c3f4152 ("Linux-2.6.12-rc2")
CC: [email protected]
Signed-off-by: Zhihao Cheng <[email protected]>
---
fs/quota/quota_tree.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
index 5f2405994280..7e65d67de9f3 100644
--- a/fs/quota/quota_tree.c
+++ b/fs/quota/quota_tree.c
@@ -71,6 +71,35 @@ static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
return ret;
}
+static inline int do_check_range(struct super_block *sb, const char *val_name,
+ uint val, uint min_val, uint max_val)
+{
+ if (val < min_val || val > max_val) {
+ quota_error(sb, "Getting %s %u out of range %u-%u",
+ val_name, val, min_val, max_val);
+ return -EUCLEAN;
+ }
+
+ return 0;
+}
+
+static int check_dquot_block_header(struct qtree_mem_dqinfo *info,
+ struct qt_disk_dqdbheader *dh)
+{
+ int err = 0;
+
+ err = do_check_range(info->dqi_sb, "dqdh_next_free",
+ le32_to_cpu(dh->dqdh_next_free), 0,
+ info->dqi_blocks - 1);
+ if (err)
+ return err;
+ err = do_check_range(info->dqi_sb, "dqdh_prev_free",
+ le32_to_cpu(dh->dqdh_prev_free), 0,
+ info->dqi_blocks - 1);
+
+ return err;
+}
+
/* Remove empty block from list and return it */
static int get_free_dqblk(struct qtree_mem_dqinfo *info)
{
@@ -85,6 +114,9 @@ static int get_free_dqblk(struct qtree_mem_dqinfo *info)
ret = read_blk(info, blk, buf);
if (ret < 0)
goto out_buf;
+ ret = check_dquot_block_header(info, dh);
+ if (ret)
+ goto out_buf;
info->dqi_free_blk = le32_to_cpu(dh->dqdh_next_free);
}
else {
@@ -232,6 +264,9 @@ static uint find_free_dqentry(struct qtree_mem_dqinfo *info,
*err = read_blk(info, blk, buf);
if (*err < 0)
goto out_buf;
+ *err = check_dquot_block_header(info, dh);
+ if (*err)
+ goto out_buf;
} else {
blk = get_free_dqblk(info);
if ((int)blk < 0) {
@@ -424,6 +459,9 @@ static int free_dqentry(struct qtree_mem_dqinfo *info, struct dquot *dquot,
goto out_buf;
}
dh = (struct qt_disk_dqdbheader *)buf;
+ ret = check_dquot_block_header(info, dh);
+ if (ret)
+ goto out_buf;
le16_add_cpu(&dh->dqdh_entries, -1);
if (!le16_to_cpu(dh->dqdh_entries)) { /* Block got free? */
ret = remove_free_dqentry(info, buf, blk);
--
2.31.1
It would be better to do more sanity checking (eg. dqdh_entries,
block no.) for the content read from quota file, which can prevent
corrupting the quota file.
Signed-off-by: Zhihao Cheng <[email protected]>
---
fs/quota/quota_tree.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
index 0fa73ca28045..0f1493e0f6d0 100644
--- a/fs/quota/quota_tree.c
+++ b/fs/quota/quota_tree.c
@@ -96,6 +96,11 @@ static int check_dquot_block_header(struct qtree_mem_dqinfo *info,
err = do_check_range(info->dqi_sb, "dqdh_prev_free",
le32_to_cpu(dh->dqdh_prev_free), 0,
info->dqi_blocks - 1);
+ if (err)
+ return err;
+ err = do_check_range(info->dqi_sb, "dqdh_entries",
+ le16_to_cpu(dh->dqdh_entries), 0,
+ qtree_dqstr_in_blk(info));
return err;
}
@@ -348,6 +353,10 @@ static int do_insert_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
}
ref = (__le32 *)buf;
newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
+ ret = do_check_range(dquot->dq_sb, "block", newblk, 0,
+ info->dqi_blocks - 1);
+ if (ret)
+ goto out_buf;
if (!newblk)
newson = 1;
if (depth == info->dqi_qtree_depth - 1) {
@@ -739,15 +748,21 @@ static int find_next_id(struct qtree_mem_dqinfo *info, qid_t *id,
goto out_buf;
}
for (i = __get_index(info, *id, depth); i < epb; i++) {
- if (ref[i] == cpu_to_le32(0)) {
+ uint blk_no = le32_to_cpu(ref[i]);
+
+ if (blk_no == 0) {
*id += level_inc;
continue;
}
+ ret = do_check_range(info->dqi_sb, "block", blk_no, 0,
+ info->dqi_blocks - 1);
+ if (ret)
+ goto out_buf;
if (depth == info->dqi_qtree_depth - 1) {
ret = 0;
goto out_buf;
}
- ret = find_next_id(info, id, le32_to_cpu(ref[i]), depth + 1);
+ ret = find_next_id(info, id, blk_no, depth + 1);
if (ret != -ENOENT)
break;
}
--
2.31.1
On Fri 23-09-22 21:45:51, Zhihao Cheng wrote:
> v1->v2:
> Add CC-stable tag in first patch.
> Rename check_free_block() -> check_dquot_block_header().
> v2->v3:
> Define do_check_range() completely in patch 1.
> Move 'dqdh_entries' checking into check_dquot_block_header().
> Do block checing later in find_next_id().
>
> Zhihao Cheng (3):
> quota: Check next/prev free block number after reading from quota file
> quota: Replace all block number checking with helper function
> quota: Add more checking after reading from quota file
>
> fs/quota/quota_tree.c | 73 ++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 61 insertions(+), 12 deletions(-)
Thanks! I've merged the patches to my tree now!
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR