[PATCH 1/1] lib: utils/ipi: buffer overrun aclint_mswi_cold_init

[Heinrich Schuchardt]

The parameter checks in aclint_mswi_cold_init() don't guard against a
buffer overrun.

mswi_hartid2data is defined as an array of SBI_HARTMASK_MAX_BITS entries.
The current check allows

    mswi->hart_count = ACLINT_MSWI_MAX_HARTS
    mswi->first_hartid = SBI_HARTMASK_MAX_BITS - 1.

With these values mswi_hartid2data will be accessed at index

    SBI_HARTMASK_MAX_BITS + SBI_HARTMASK_MAX_BITS - 2.

We have to check the sum of mswi->first_hartid and mswi->hart_count.

Furthermore mswi->hart_count = 0 would not make much sense.

Addresses-Coverity-ID: 1529705 ("Out-of-bounds write")
5a049fe1d6a5 ("lib: utils/ipi: Add ACLINT MSWI library")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 lib/utils/ipi/aclint_mswi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/utils/ipi/aclint_mswi.c b/lib/utils/ipi/aclint_mswi.c
index 6b004cb..ac8570b 100644
--- a/lib/utils/ipi/aclint_mswi.c
+++ b/lib/utils/ipi/aclint_mswi.c
@@ -75,8 +75,8 @@ int aclint_mswi_cold_init(struct aclint_mswi_data *mswi)
 	/* Sanity checks */
 	if (!mswi || (mswi->addr & (ACLINT_MSWI_ALIGN - 1)) ||
 	    (mswi->size < (mswi->hart_count * sizeof(u32))) ||
-	    (mswi->first_hartid >= SBI_HARTMASK_MAX_BITS) ||
-	    (mswi->hart_count > ACLINT_MSWI_MAX_HARTS))
+	    (mswi->first_hartid + mswi->hart_count > SBI_HARTMASK_MAX_BITS) ||
+	    (!mswi->hart_count || mswi->hart_count > ACLINT_MSWI_MAX_HARTS))
 		return SBI_EINVAL;
 
 	/* Update MSWI hartid table */
-- 
2.39.2