diff options
| author | Daniel Mentz <danielmentz@google.com> | 2024-10-01 18:53:57 -0700 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2024-10-08 18:37:48 +0100 |
| commit | f63237f54cf18448728201a65e6c82018e807cd9 (patch) | |
| tree | f58b345b48d037b3d37515f3725e6548f7b0fa8c /drivers/iommu | |
| parent | 0dfe314cdd0d378f96bb9c6bdc05c8120f48606d (diff) | |
iommu/arm-smmu-v3: Fix last_sid_idx calculation for sid_bits==32
The function arm_smmu_init_strtab_2lvl uses the expression
((1 << smmu->sid_bits) - 1)
to calculate the largest StreamID value. However, this fails for the
maximum allowed value of SMMU_IDR1.SIDSIZE which is 32. The C standard
states:
"If the value of the right operand is negative or is greater than or
equal to the width of the promoted left operand, the behavior is
undefined."
With smmu->sid_bits being 32, the prerequisites for undefined behavior
are met. We observed that the value of (1 << 32) is 1 and not 0 as we
initially expected.
Similar bit shift operations in arm_smmu_init_strtab_linear seem to not
be affected, because it appears to be unlikely for an SMMU to have
SMMU_IDR1.SIDSIZE set to 32 but then not support 2-level Stream tables
This issue was found by Ryan Huang <tzukui@google.com> on our team.
Fixes: ce410410f1a7 ("iommu/arm-smmu-v3: Add arm_smmu_strtab_l1/2_idx()")
Signed-off-by: Daniel Mentz <danielmentz@google.com>
Link: https://lore.kernel.org/r/20241002015357.1766934-1-danielmentz@google.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers/iommu')
| -rw-r--r-- | drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 737c5b882355..b55327d6058e 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -3625,7 +3625,7 @@ static int arm_smmu_init_strtab_2lvl(struct arm_smmu_device *smmu) u32 l1size; struct arm_smmu_strtab_cfg *cfg = &smmu->strtab_cfg; unsigned int last_sid_idx = - arm_smmu_strtab_l1_idx((1 << smmu->sid_bits) - 1); + arm_smmu_strtab_l1_idx((1ULL << smmu->sid_bits) - 1); /* Calculate the L1 size, capped to the SIDSIZE. */ cfg->l2.num_l1_ents = min(last_sid_idx + 1, STRTAB_MAX_L1_ENTRIES); |