This is a note to let you know that I've just added the patch titled
blk-throttle: check for overflow in calculate_bytes_allowed
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
blk-throttle-check-for-overflow-in-calculate_bytes_allowed.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2dd710d476f2f1f6eaca884f625f69ef4389ed40 Mon Sep 17 00:00:00 2001
From: Khazhismel Kumykov <khazhy@xxxxxxxxxxxx>
Date: Fri, 20 Oct 2023 15:36:17 -0700
Subject: blk-throttle: check for overflow in calculate_bytes_allowed
From: Khazhismel Kumykov <khazhy@xxxxxxxxxxxx>
commit 2dd710d476f2f1f6eaca884f625f69ef4389ed40 upstream.
Inexact, we may reject some not-overflowing values incorrectly, but
they'll be on the order of exabytes allowed anyways.
This fixes divide error crash on x86 if bps_limit is not configured or
is set too high in the rare case that jiffy_elapsed is greater than HZ.
Fixes: e8368b57c006 ("blk-throttle: use calculate_io/bytes_allowed() for throtl_trim_slice()")
Fixes: 8d6bbaada2e0 ("blk-throttle: prevent overflow while calculating wait time")
Signed-off-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231020223617.2739774-1-khazhy@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-throttle.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -723,6 +723,12 @@ static unsigned int calculate_io_allowed
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);
}
Patches currently in stable-queue which might be from khazhy@xxxxxxxxxxxx are
queue-6.5/blk-throttle-check-for-overflow-in-calculate_bytes_allowed.patch
