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exfat: fix divide-by-zero in exfat_allocate_bitmap 

The variable max_ra_count can be 0 in exfat_allocate_bitmap(),
which causes a divide-by-zero error in the subsequent modulo operation
(i % max_ra_count), leading to a system crash.
When max_ra_count is 0, it means that readahead is not used. This patch
load the bitmap without readahead.

Fixes: 9fd688678d ("exfat: optimize allocation bitmap loading time")
Reported-by: Jiaming Zhang <r772577952@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Namjae Jeon 2025-11-18 11:10:26 +09:00
parent 866cba3675
commit d70a5804c5
1 changed files with 1 additions and 1 deletions
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2
fs/exfat/balloc.c
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@ -106,7 +106,7 @@ static int exfat_allocate_bitmap(struct super_block *sb,
(PAGE_SHIFT - sb->s_blocksize_bits); (PAGE_SHIFT - sb->s_blocksize_bits);
for (i = 0; i < sbi->map_sectors; i++) { for (i = 0; i < sbi->map_sectors; i++) {
/* Trigger the next readahead in advance. */ /* Trigger the next readahead in advance. */
if (0 == (i % max_ra_count)) { if (max_ra_count && 0 == (i % max_ra_count)) {
blk_start_plug(&plug); blk_start_plug(&plug);
for (j = i; j < min(max_ra_count, sbi->map_sectors - i) + i; j++) for (j = i; j < min(max_ra_count, sbi->map_sectors - i) + i; j++)
sb_breadahead(sb, sector + j); sb_breadahead(sb, sector + j);