[f2fs-dev] [PATCH] mkfs.f2fs: catch total_zones=0 instead of crashing

[Eric Biggers <ebiggers@kernel.org>]

From: Eric Biggers <ebiggers@google.com>

Cleanly report an error instead of dividing by 0 (causing a floating
point exception) in the following case:

	truncate -s 16M img && mkfs.f2fs img

Note that this is a minimal fix; it appears that overly-small images
still cause various integer overflows in f2fs_prepare_super_block().

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 mkfs/f2fs_format.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
index 7cd5815..40ac589 100644
--- a/mkfs/f2fs_format.c
+++ b/mkfs/f2fs_format.c
@@ -467,7 +467,8 @@ static int f2fs_prepare_super_block(void)
 
 	total_zones = get_sb(segment_count) / (c.segs_per_zone) -
 							total_meta_zones;
-
+	if (total_zones == 0)
+		goto too_small;
 	set_sb(section_count, total_zones * c.secs_per_zone);
 
 	set_sb(segment_count_main, get_sb(section_count) * c.segs_per_sec);
@@ -497,8 +498,7 @@ static int f2fs_prepare_super_block(void)
 			c.sector_size < zone_align_start_offset) ||
 		(get_sb(segment_count_main) - NR_CURSEG_TYPE) <
 						c.reserved_segments) {
-		MSG(0, "\tError: Device size is not sufficient for F2FS volume\n");
-		return -1;
+		goto too_small;
 	}
 
 	if (c.vol_uuid) {
@@ -612,6 +612,10 @@ static int f2fs_prepare_super_block(void)
 	}
 
 	return 0;
+
+too_small:
+	MSG(0, "\tError: Device size is not sufficient for F2FS volume\n");
+	return -1;
 }
 
 static int f2fs_init_sit_area(void)

base-commit: 6148db344eb25b23a7cbde36d026011cd15b6143
-- 
2.37.1



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