Re: [PATCH v7 24/29] dyndbg: pin class param storage to u32
From: sashiko-bot@kernel.org
Date: 2026-07-21 21:10:53
Also in:
dri-devel
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Medium] Bitwise shift out-of-bounds on 32-bit architectures when evaluating `BIT(bi)` in `ddebug_apply_class_bitmap()`. --
--- Patch [24]: [PATCH v7 24/29] dyndbg: pin class param storage to u32 ---commit 87a65c25e24b4e05bdc18ddf16105e9237d922db Author: Jim Cromie [off-list ref] dyndbg: pin class param storage to u32 This commit changes the bits and lvl fields in struct ddebug_class_param to use u32 instead of unsigned long. This ensures consistent sizing across different architectures.
quoted hunk ↗ jump to hunk
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 59e3c0eccbede..60b67face46e1 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c
[ ... ]
quoted hunk ↗ jump to hunk
@@ -643,24 +643,27 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp, int bi, ct; if (*new_bits != old_bits) - v2pr_info("apply bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits, + v2pr_info("apply bitmap: 0x%x to: 0x%x for %s\n", *new_bits, old_bits, query_modname ?: "'*'"); for (bi = 0; bi < map->length; bi++) { - if (test_bit(bi, new_bits) == test_bit(bi, &old_bits)) + bool new_b = !!(*new_bits & BIT(bi)); + bool old_b = !!(old_bits & BIT(bi));
[Severity: Medium] Can this result in an out-of-bounds bitwise shift on 32-bit architectures? The BIT(bi) macro expands to (1UL << bi). On 32-bit systems, 1UL is 32 bits wide. If a module defines a classmap with 32 or more classes (map->length >= 32), shifting by 32 or more triggers undefined behavior. On most 32-bit architectures, the CPU masks the shift count modulo 32, meaning BIT(32) evaluates to BIT(0). This causes the loop to incorrectly re-evaluate and alter class 0 instead of processing the intended class, leading to incorrect functional behavior when configuring dynamic debug.
+ if (new_b == old_b) continue; snprintf(query, QUERY_SIZE, "class %s %c%s", map->class_names[bi],
-- Sashiko AI review · https://sashiko.dev/#/patchset/20260721-dd-maint-2-v7-0-010fbe73b311@gmail.com?part=24