In the quest to remove all stack VLA usage from the kernel[1], this switches to using a maximum size and adds sanity checks. Additionally cleans up some of the int-vs-u32 usage and adds additional bounds checking. As it currently stands, this will always be 8 bytes until the ABI changes.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qpxydaacu1rq...@mail.gmail.com Cc: Christoffer Dall <christoffer.d...@arm.com> Cc: Marc Zyngier <marc.zyng...@arm.com> Cc: Eric Auger <eric.au...@redhat.com> Cc: Andre Przywara <andre.przyw...@arm.com> Cc: linux-arm-ker...@lists.infradead.org Cc: kvmarm@lists.cs.columbia.edu Signed-off-by: Kees Cook <keesc...@chromium.org> --- virt/kvm/arm/vgic/vgic-its.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c index 4ed79c939fb4..3143fc047fcf 100644 --- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -168,8 +168,14 @@ struct vgic_its_abi { int (*commit)(struct vgic_its *its); }; +#define ABI_0_ESZ 8 +#define ESZ_MAX ABI_0_ESZ + static const struct vgic_its_abi its_table_abi_versions[] = { - [0] = {.cte_esz = 8, .dte_esz = 8, .ite_esz = 8, + [0] = { + .cte_esz = ABI_0_ESZ, + .dte_esz = ABI_0_ESZ, + .ite_esz = ABI_0_ESZ, .save_tables = vgic_its_save_tables_v0, .restore_tables = vgic_its_restore_tables_v0, .commit = vgic_its_commit_v0, @@ -180,10 +186,12 @@ static const struct vgic_its_abi its_table_abi_versions[] = { inline const struct vgic_its_abi *vgic_its_get_abi(struct vgic_its *its) { + if (WARN_ON(its->abi_rev >= NR_ITS_ABIS)) + return NULL; return &its_table_abi_versions[its->abi_rev]; } -int vgic_its_set_abi(struct vgic_its *its, int rev) +static int vgic_its_set_abi(struct vgic_its *its, u32 rev) { const struct vgic_its_abi *abi; @@ -1881,16 +1889,19 @@ typedef int (*entry_fn_t)(struct vgic_its *its, u32 id, void *entry, * Return: < 0 on error, 0 if last element was identified, 1 otherwise * (the last element may not be found on second level tables) */ -static int scan_its_table(struct vgic_its *its, gpa_t base, int size, int esz, +static int scan_its_table(struct vgic_its *its, gpa_t base, int size, u32 esz, int start_id, entry_fn_t fn, void *opaque) { struct kvm *kvm = its->dev->kvm; unsigned long len = size; int id = start_id; gpa_t gpa = base; - char entry[esz]; + char entry[ESZ_MAX]; int ret; + if (WARN_ON(esz > ESZ_MAX)) + return -EINVAL; + memset(entry, 0, esz); while (len > 0) { -- 2.17.1 -- Kees Cook Pixel Security _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
