From: Darrick J. Wong Date: Thu, 14 May 2015 23:11:50 +0000 (-0400) Subject: jbd2: fix r_count overflows leading to buffer overflow in journal recovery X-Git-Tag: v3.2.70~70 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f6a2bcc01bc9ed73bfb4d698da94ed2a5fcb18c;p=pandora-kernel.git jbd2: fix r_count overflows leading to buffer overflow in journal recovery commit e531d0bceb402e643a4499de40dd3fa39d8d2e43 upstream. 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 Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara [bwh: Backported to 3.2: journal checksumming is not supported, so only the first fix is needed] Signed-off-by: Ben Hutchings --- diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c index da6d7baf1390..421834bae020 100644 --- a/fs/jbd2/recovery.c +++ b/fs/jbd2/recovery.c @@ -711,11 +711,16 @@ static int scan_revoke_records(journal_t *journal, struct buffer_head *bh, { jbd2_journal_revoke_header_t *header; int offset, max; + __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 (rcount > journal->j_blocksize) + return -EINVAL; + max = rcount; if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) record_len = 8;