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| author | Khazhismel Kumykov <khazhy@chromium.org> | 2023-10-21 01:36:17 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-10-21 03:38:17 +0300 |
| commit | 2dd710d476f2f1f6eaca884f625f69ef4389ed40 (patch) | |
| tree | bcb7b766b44f98e9223d099700c3b986c6d2e92c /block/blk-throttle.c | |
| parent | c3414550cb0d4dfad1816ee14ff1f44819d270db (diff) | |
| download | linux-2dd710d476f2f1f6eaca884f625f69ef4389ed40.tar.xz | |
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.c | 6 |
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); } |