f2fs: sanity check checkpoint segno and blkoff

commit 15d3042a937c13f5d9244241c7a9c8416ff6e82a upstream.

Make sure segno and blkoff read from raw image are valid.

Cc: stable@vger.kernel.org
Signed-off-by: Jin Qian <jinqian@google.com>
[Jaegeuk Kim: adjust minor coding style]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
[AmitP: Found in Android Security bulletin for Aug'17, fixes CVE-2017-10663]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 86e1cb8..4f66636 100644 (file)
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1078,6 +1078,8 @@ static int sanity_check_ckpt(struct f2fs_sb_info *sbi)
        unsigned int total, fsmeta;
        struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
        struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+       unsigned int main_segs, blocks_per_seg;
+       int i;
 
        total = le32_to_cpu(raw_super->segment_count);
        fsmeta = le32_to_cpu(raw_super->segment_count_ckpt);
@@ -1089,6 +1091,20 @@ static int sanity_check_ckpt(struct f2fs_sb_info *sbi)
        if (unlikely(fsmeta >= total))
                return 1;
 
+       main_segs = le32_to_cpu(raw_super->segment_count_main);
+       blocks_per_seg = sbi->blocks_per_seg;
+
+       for (i = 0; i < NR_CURSEG_NODE_TYPE; i++) {
+               if (le32_to_cpu(ckpt->cur_node_segno[i]) >= main_segs ||
+                       le16_to_cpu(ckpt->cur_node_blkoff[i]) >= blocks_per_seg)
+                       return 1;
+       }
+       for (i = 0; i < NR_CURSEG_DATA_TYPE; i++) {
+               if (le32_to_cpu(ckpt->cur_data_segno[i]) >= main_segs ||
+                       le16_to_cpu(ckpt->cur_data_blkoff[i]) >= blocks_per_seg)
+                       return 1;
+       }
+
        if (unlikely(f2fs_cp_error(sbi))) {
                f2fs_msg(sbi->sb, KERN_ERR, "A bug case: need to run fsck");
                return 1;