+From 09fe1fd2a1f9efc3091b4fc61f1876d0785956a8 Mon Sep 17 00:00:00 2001
+From: Theodore Ts'o <tytso@mit.edu>
+Date: Sun, 1 Sep 2019 00:59:16 -0400
+Subject: libsupport: add checks to prevent buffer overrun bugs in quota code
+
+A maliciously corrupted file systems can trigger buffer overruns in
+the quota code used by e2fsck. To fix this, add sanity checks to the
+quota header fields as well as to block number references in the quota
+tree.
+
+Addresses: CVE-2019-5094
+Addresses: TALOS-2019-0887
+Signed-off-by: Theodore Ts'o <tytso@mit.edu>
+(cherry picked from commit 8dbe7b475ec5e91ed767239f0e85880f416fc384)
+---
+ lib/support/mkquota.c | 1 +
+ lib/support/quotaio_tree.c | 71 ++++++++++++++++++++++++++++++----------------
+ lib/support/quotaio_v2.c | 28 ++++++++++++++++++
+ 3 files changed, 76 insertions(+), 24 deletions(-)
+
+--- a/lib/support/mkquota.c
++++ b/lib/support/mkquota.c
+@@ -671,6 +671,7 @@ errcode_t quota_compare_and_update(quota
+ err = qh.qh_ops->scan_dquots(&qh, scan_dquots_callback, &scan_data);
+ if (err) {
+ log_debug("Error scanning dquots");
++ *usage_inconsistent = 1;
+ goto out_close_qh;
+ }
+
+--- a/lib/support/quotaio_tree.c
++++ b/lib/support/quotaio_tree.c
+@@ -540,6 +540,17 @@ struct dquot *qtree_read_dquot(struct qu
+ return dquot;
+ }
+
++static int check_reference(struct quota_handle *h, unsigned int blk)
++{
++ if (blk >= h->qh_info.u.v2_mdqi.dqi_qtree.dqi_blocks) {
++ log_err("Illegal reference (%u >= %u) in %s quota file",
++ blk, h->qh_info.u.v2_mdqi.dqi_qtree.dqi_blocks,
++ quota_type2name(h->qh_type));
++ return -1;
++ }
++ return 0;
++}
++
+ /*
+ * Scan all dquots in file and call callback on each
+ */
+@@ -558,7 +569,7 @@ static int report_block(struct dquot *dq
+ int entries, i;
+
+ if (!buf)
+- return 0;
++ return -1;
+
+ set_bit(bitmap, blk);
+ read_blk(dquot->dq_h, blk, buf);
+@@ -580,23 +591,12 @@ static int report_block(struct dquot *dq
+ return entries;
+ }
+
+-static void check_reference(struct quota_handle *h, unsigned int blk)
+-{
+- if (blk >= h->qh_info.u.v2_mdqi.dqi_qtree.dqi_blocks)
+- log_err("Illegal reference (%u >= %u) in %s quota file. "
+- "Quota file is probably corrupted.\n"
+- "Please run e2fsck (8) to fix it.",
+- blk,
+- h->qh_info.u.v2_mdqi.dqi_qtree.dqi_blocks,
+- quota_type2name(h->qh_type));
+-}
+-
+ static int report_tree(struct dquot *dquot, unsigned int blk, int depth,
+ char *bitmap,
+ int (*process_dquot) (struct dquot *, void *),
+ void *data)
+ {
+- int entries = 0, i;
++ int entries = 0, ret, i;
+ dqbuf_t buf = getdqbuf();
+ __le32 *ref = (__le32 *) buf;
+
+@@ -607,22 +607,40 @@ static int report_tree(struct dquot *dqu
+ if (depth == QT_TREEDEPTH - 1) {
+ for (i = 0; i < QT_BLKSIZE >> 2; i++) {
+ blk = ext2fs_le32_to_cpu(ref[i]);
+- check_reference(dquot->dq_h, blk);
+- if (blk && !get_bit(bitmap, blk))
+- entries += report_block(dquot, blk, bitmap,
+- process_dquot, data);
++ if (check_reference(dquot->dq_h, blk)) {
++ entries = -1;
++ goto errout;
++ }
++ if (blk && !get_bit(bitmap, blk)) {
++ ret = report_block(dquot, blk, bitmap,
++ process_dquot, data);
++ if (ret < 0) {
++ entries = ret;
++ goto errout;
++ }
++ entries += ret;
++ }
+ }
+ } else {
+ for (i = 0; i < QT_BLKSIZE >> 2; i++) {
+ blk = ext2fs_le32_to_cpu(ref[i]);
+ if (blk) {
+- check_reference(dquot->dq_h, blk);
+- entries += report_tree(dquot, blk, depth + 1,
+- bitmap, process_dquot,
+- data);
++ if (check_reference(dquot->dq_h, blk)) {
++ entries = -1;
++ goto errout;
++ }
++ ret = report_tree(dquot, blk, depth + 1,
++ bitmap, process_dquot,
++ data);
++ if (ret < 0) {
++ entries = ret;
++ goto errout;
++ }
++ entries += ret;
+ }
+ }
+ }
++errout:
+ freedqbuf(buf);
+ return entries;
+ }
+@@ -642,6 +660,7 @@ int qtree_scan_dquots(struct quota_handl
+ int (*process_dquot) (struct dquot *, void *),
+ void *data)
+ {
++ int ret;
+ char *bitmap;
+ struct v2_mem_dqinfo *v2info = &h->qh_info.u.v2_mdqi;
+ struct qtree_mem_dqinfo *info = &v2info->dqi_qtree;
+@@ -655,10 +674,14 @@ int qtree_scan_dquots(struct quota_handl
+ ext2fs_free_mem(&dquot);
+ return -1;
+ }
+- v2info->dqi_used_entries = report_tree(dquot, QT_TREEOFF, 0, bitmap,
+- process_dquot, data);
++ ret = report_tree(dquot, QT_TREEOFF, 0, bitmap, process_dquot, data);
++ if (ret < 0)
++ goto errout;
++ v2info->dqi_used_entries = ret;
+ v2info->dqi_data_blocks = find_set_bits(bitmap, info->dqi_blocks);
++ ret = 0;
++errout:
+ ext2fs_free_mem(&bitmap);
+ ext2fs_free_mem(&dquot);
+- return 0;
++ return ret;
+ }
+--- a/lib/support/quotaio_v2.c
++++ b/lib/support/quotaio_v2.c
+@@ -175,6 +175,8 @@ static int v2_check_file(struct quota_ha
+ static int v2_init_io(struct quota_handle *h)
+ {
+ struct v2_disk_dqinfo ddqinfo;
++ struct v2_mem_dqinfo *info;
++ __u64 filesize;
+
+ h->qh_info.u.v2_mdqi.dqi_qtree.dqi_entry_size =
+ sizeof(struct v2r1_disk_dqblk);
+@@ -185,6 +187,32 @@ static int v2_init_io(struct quota_handl
+ sizeof(ddqinfo)) != sizeof(ddqinfo))
+ return -1;
+ v2_disk2memdqinfo(&h->qh_info, &ddqinfo);
++
++ /* Check to make sure quota file info is sane */
++ info = &h->qh_info.u.v2_mdqi;
++ if (ext2fs_file_get_lsize(h->qh_qf.e2_file, &filesize))
++ return -1;
++ if ((filesize > (1U << 31)) ||
++ (info->dqi_qtree.dqi_blocks >
++ (filesize + QT_BLKSIZE - 1) >> QT_BLKSIZE_BITS)) {
++ log_err("Quota inode %u corrupted: file size %llu; "
++ "dqi_blocks %u", h->qh_qf.ino,
++ filesize, info->dqi_qtree.dqi_blocks);
++ return -1;
++ }
++ if (info->dqi_qtree.dqi_free_blk >= info->dqi_qtree.dqi_blocks) {
++ log_err("Quota inode %u corrupted: free_blk %u; dqi_blocks %u",
++ h->qh_qf.ino, info->dqi_qtree.dqi_free_blk,
++ info->dqi_qtree.dqi_blocks);
++ return -1;
++ }
++ if (info->dqi_qtree.dqi_free_entry >= info->dqi_qtree.dqi_blocks) {
++ log_err("Quota inode %u corrupted: free_entry %u; "
++ "dqi_blocks %u", h->qh_qf.ino,
++ info->dqi_qtree.dqi_free_entry,
++ info->dqi_qtree.dqi_blocks);
++ return -1;
++ }
+ return 0;
+ }
+
projects / openwrt / openwrt.git / commitdiff