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authorDarrick J. Wong <darrick.wong@oracle.com>2015-05-14 19:11:50 -0400
committerSasha Levin <sasha.levin@oracle.com>2015-06-10 13:42:24 -0400
commitd4842a5455e20003780bd81c429065756ed1ebcb (patch)
treedf785995f13be1413977cdbec8d5a7c6dbfbe2b1
parentc164d09cd8eb3f6b8c183409695dc0eb3c4c503a (diff)
downloadlinux-linaro-stable-d4842a5455e20003780bd81c429065756ed1ebcb.tar.gz
jbd2: fix r_count overflows leading to buffer overflow in journal recovery
[ Upstream commit e531d0bceb402e643a4499de40dd3fa39d8d2e43 ] The journal revoke block recovery code does not check r_count for sanity, which means that an evil value of r_count could result in the kernel reading off the end of the revoke table and into whatever garbage lies beyond. This could crash the kernel, so fix that. However, in testing this fix, I discovered that the code to write out the revoke tables also was not correctly checking to see if the block was full -- the current offset check is fine so long as the revoke table space size is a multiple of the record size, but this is not true when either journal_csum_v[23] are set. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--fs/jbd2/recovery.c10
-rw-r--r--fs/jbd2/revoke.c18
2 files changed, 19 insertions, 9 deletions
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index bcbef08a4d8f..a5f72a36c6c8 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -839,15 +839,23 @@ static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
{
jbd2_journal_revoke_header_t *header;
int offset, max;
+ int csum_size = 0;
+ __u32 rcount;
int record_len = 4;
header = (jbd2_journal_revoke_header_t *) bh->b_data;
offset = sizeof(jbd2_journal_revoke_header_t);
- max = be32_to_cpu(header->r_count);
+ rcount = be32_to_cpu(header->r_count);
if (!jbd2_revoke_block_csum_verify(journal, header))
return -EINVAL;
+ if (jbd2_journal_has_csum_v2or3(journal))
+ csum_size = sizeof(struct jbd2_journal_revoke_tail);
+ if (rcount > journal->j_blocksize - csum_size)
+ return -EINVAL;
+ max = rcount;
+
if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
record_len = 8;
diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c
index c6cbaef2bda1..14214da80eb8 100644
--- a/fs/jbd2/revoke.c
+++ b/fs/jbd2/revoke.c
@@ -577,7 +577,7 @@ static void write_one_revoke_record(journal_t *journal,
{
int csum_size = 0;
struct buffer_head *descriptor;
- int offset;
+ int sz, offset;
journal_header_t *header;
/* If we are already aborting, this all becomes a noop. We
@@ -594,9 +594,14 @@ static void write_one_revoke_record(journal_t *journal,
if (jbd2_journal_has_csum_v2or3(journal))
csum_size = sizeof(struct jbd2_journal_revoke_tail);
+ if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
+ sz = 8;
+ else
+ sz = 4;
+
/* Make sure we have a descriptor with space left for the record */
if (descriptor) {
- if (offset >= journal->j_blocksize - csum_size) {
+ if (offset + sz > journal->j_blocksize - csum_size) {
flush_descriptor(journal, descriptor, offset, write_op);
descriptor = NULL;
}
@@ -619,16 +624,13 @@ static void write_one_revoke_record(journal_t *journal,
*descriptorp = descriptor;
}
- if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) {
+ if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
* ((__be64 *)(&descriptor->b_data[offset])) =
cpu_to_be64(record->blocknr);
- offset += 8;
-
- } else {
+ else
* ((__be32 *)(&descriptor->b_data[offset])) =
cpu_to_be32(record->blocknr);
- offset += 4;
- }
+ offset += sz;
*offsetp = offset;
}