6.18-stable review patch. If anyone has any objections, please let me know.
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From: Namjae Jeon linkinjeon@kernel.org
[ Upstream commit d70a5804c563b5e34825353ba9927509df709651 ]
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: 9fd688678dd8 ("exfat: optimize allocation bitmap loading time") Reported-by: Jiaming Zhang r772577952@gmail.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/exfat/balloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index 2d2d510f2372c..0b6466b3490a0 100644 --- a/fs/exfat/balloc.c +++ b/fs/exfat/balloc.c @@ -106,7 +106,7 @@ static int exfat_allocate_bitmap(struct super_block *sb, (PAGE_SHIFT - sb->s_blocksize_bits); for (i = 0; i < sbi->map_sectors; i++) { /* 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); for (j = i; j < min(max_ra_count, sbi->map_sectors - i) + i; j++) sb_breadahead(sb, sector + j);