Merge tag 'block-6.6-2023-10-27' of git://git.kernel.dk/linux

2dc4e0f4 · Linus Torvalds <[email protected]> · 2023-10-27 14:01:59 -10:00

Pull block fix from Jens Axboe:
 "Just a single fix for a potential divide-by-zero, introduced in this
  cycle"

* tag 'block-6.6-2023-10-27' of git://git.kernel.dk/linux:
  blk-throttle: check for overflow in calculate_bytes_allowed

Commit: 2dc4e0f45593abc53d58d0073b3b314f864c522b
Parents: 832328c9 · 2dd710d4

Merge commit. Changes below are compared with the first parent: 832328c9.

Changes

1 files changed · +6 −0

File	Status	Add	Del	Content
block/blk-throttle.c	modified	+6	−0	View file

block/blk-throttle.c

View file

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 38a881c..13e4377 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -723,6 +723,12 @@ static unsigned int calculate_io_allowed(u32 iops_limit,
 
 static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long jiffy_elapsed)
 {
+	/*
+	 * Can result be wider than 64 bits?
+	 * We check against 62, not 64, due to ilog2 truncation.
+	 */
+	if (ilog2(bps_limit) + ilog2(jiffy_elapsed) - ilog2(HZ) > 62)
+		return U64_MAX;
 	return mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed, (u64)HZ);
 }
 