e2fsck: make sure get_backup_sb() works when ctx is NULL

The print_e2fsck_message() function can call get_backup_sb() with the ctx variable set to NULL. In that case, we can't dereference ctx->filesystem_name; instead, we can get the size of the file system from the ext2fs_block_count(fs->super). Addresses-Coverity-Bug: 1596517 Addresses-Coverity-Bug: 1596505 Fixes: b53ce78 ("e2fsck: don't try backup superblocks beyond...") Signed-off-by: Theodore Ts'o <[email protected]>
tytso · Apr 24, 2024 · a12302f · a12302f
1 parent 49125d4
commit a12302f
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/e2fsck/util.c b/e2fsck/util.c
@@ -592,9 +592,11 @@ blk64_t get_backup_sb(e2fsck_t ctx, ext2_filsys fs, const char *name,
 		blk_t this_bpg = bpg ? bpg : blocksize * 8;
 		blk64_t	num_blocks;
 
-		if (ext2fs_get_device_size2(ctx->filesystem_name,
-					    blocksize,
-					    &num_blocks) == 0) {
+		if (fs && fs->super) {
+			num_blocks = ext2fs_blocks_count(fs->super);
+		} else if (ctx && ext2fs_get_device_size2(ctx->filesystem_name,
+							  blocksize,
+							  &num_blocks) == 0) {
 			limit = num_blocks / this_bpg;
 		} else {
 			/* If we can't figure out the device size,