File 0001-fsck.gfs2-Tighten-offset-check-in-check_ea... of Package gfs2-utils

Overview Repositories Revisions Requests Users Attributes Meta

File 0001-fsck.gfs2-Tighten-offset-check-in-check_eattr_entrie.patch of Package gfs2-utils

From caab270a739d619cfa3b8d4c57789cb6b1ef94e8 Mon Sep 17 00:00:00 2001
From: Andrew Price <anprice@redhat.com>
Date: Thu, 11 May 2023 17:04:34 +0100
Subject: [PATCH] fsck.gfs2: Tighten offset check in check_eattr_entries()

The "offset >= bsize" check is insufficient as it doesn't detect invalid
ea_header offsets less than one ea_header from the end of the block.
This fixes an unlikely fsck.gfs2 buffer over-read that can occur.

For the bug to occur:
1. The last valid xattr header must not have GFS2_EAFLAG_LAST set
2. Its ea_rec_len must result in an offset of the next xattr within 15
   bytes of the end of the block

A segfault can then occur if this region contains non-zero data that
results in the loop continuing with another bad offset and another bad
read, and so on.

Signed-off-by: Andrew Price <anprice@redhat.com>
---
 gfs2/fsck/metawalk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gfs2/fsck/metawalk.c b/gfs2/fsck/metawalk.c
index 66316e4d864c..819a7e670f73 100644
--- a/gfs2/fsck/metawalk.c
+++ b/gfs2/fsck/metawalk.c
@@ -846,6 +846,7 @@ static int check_eattr_entries(struct fsck_cx *cx, struct lgfs2_inode *ip,
 	int i;
 	int error = 0, err;
 	uint32_t offset = (uint32_t)sizeof(struct gfs2_meta_header);
+	uint32_t offset_limit = ip->i_sbd->sd_bsize - sizeof(struct gfs2_ea_header);
 
 	if (!pass->check_eattr_entry)
 		return 0;
@@ -894,7 +895,7 @@ static int check_eattr_entries(struct fsck_cx *cx, struct lgfs2_inode *ip,
 		}
 		offset += be32_to_cpu(ea_hdr->ea_rec_len);
 		if (ea_hdr->ea_flags & GFS2_EAFLAG_LAST ||
-		   offset >= ip->i_sbd->sd_bsize || ea_hdr->ea_rec_len == 0){
+		    offset > offset_limit || ea_hdr->ea_rec_len == 0) {
 			break;
 		}
 		ea_hdr_prev = ea_hdr;
-- 
2.35.3

Places

File 0001-fsck.gfs2-Tighten-offset-check-in-check_eattr_entrie.patch of Package gfs2-utils

Places