CVE-2023-54242 — block, bfq: Fix division by zero error on zero wsum

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

block, bfq: Fix division by zero error on zero wsum

When the weighted sum is zero the calculation of limit causes a division by zero error. Fix this by continuing to the next level.

This was discovered by running as root:

stress-ng --ioprio 0

Fixes divison by error oops:

[ 521.450556] divide error: 0000 [#1] SMP NOPTI [ 521.450766] CPU: 2 PID: 2684464 Comm: stress-ng-iopri Not tainted 6.2.1-1280.native #1 [ 521.451117] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.1-0-g3208b098f51a-prebuilt.qemu.org 04/01/2014 [ 521.451627] RIP: 0010:bfqq_request_over_limit+0x207/0x400 [ 521.451875] Code: 01 48 8d 0c c8 74 0b 48 8b 82 98 00 00 00 48 8d 0c c8 8b 85 34 ff ff ff 48 89 ca 41 0f af 41 50 48 d1 ea 48 98 48 01 d0 31 d2 <48> f7 f1 41 39 41 48 89 85 34 ff ff ff 0f 8c 7b 01 00 00 49 8b 44 [ 521.452699] RSP: 0018:ffffb1af84eb3948 EFLAGS: 00010046 [ 521.452938] RAX: 000000000000003c RBX: 0000000000000000 RCX: 0000000000000000 [ 521.453262] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffb1af84eb3978 [ 521.453584] RBP: ffffb1af84eb3a30 R08: 0000000000000001 R09: ffff8f88ab8a4ba0 [ 521.453905] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8f88ab8a4b18 [ 521.454224] R13: ffff8f8699093000 R14: 0000000000000001 R15: ffffb1af84eb3970 [ 521.454549] FS: 00005640b6b0b580(0000) GS:ffff8f88b3880000(0000) knlGS:0000000000000000 [ 521.454912] CS: 0010 DS: 0000 ES: 0000 CR0: 000…

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CVE-2023-54242 — block, bfq: Fix division by zero error on zero wsum