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authorKhazhismel Kumykov <khazhy@chromium.org>2023-10-20 15:36:17 -0700
committerJens Axboe <axboe@kernel.dk>2023-10-20 18:38:17 -0600
commit2dd710d476f2f1f6eaca884f625f69ef4389ed40 (patch)
treebcb7b766b44f98e9223d099700c3b986c6d2e92c /block/blk-throttle.c
parentc3414550cb0d4dfad1816ee14ff1f44819d270db (diff)
blk-throttle: check for overflow in calculate_bytes_allowed
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@google.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20231020223617.2739774-1-khazhy@google.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-throttle.c')
-rw-r--r--block/blk-throttle.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 38a881cf97d0..13e4377a8b28 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);
}