coresight: Fix signedness bug in tmc_etr_buf_insert_barrier_packet()

commit f67bc15e526bb9920683ad6c1891ff9e08981335 upstream.

This code generates a Smatch warning:

    drivers/hwtracing/coresight/coresight-tmc-etr.c:947 tmc_etr_buf_insert_barrier_packet()
    error: uninitialized symbol 'bufp'.

The problem is that if tmc_sg_table_get_data() returns -EINVAL, then
when we test if "len < CORESIGHT_BARRIER_PKT_SIZE", the negative "len"
value is type promoted to a high unsigned long value which is greater
than CORESIGHT_BARRIER_PKT_SIZE.  Fix this bug by adding an explicit
check for error codes.

Fixes: 6035fcaa30da ("coresight: tmc-etr: Add transparent buffer management")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/7d33e244-d8b9-4c27-9653-883a13534b01@kili.mountain
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index ed77c7f7b344b546222e5e95bae0505d2b0a6d5b..763463776a0e1352d5cb784a6a31890d3bb2cf7a 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -909,7 +909,7 @@ tmc_etr_buf_insert_barrier_packet(struct etr_buf *etr_buf, u64 offset)
 
        len = tmc_etr_buf_get_data(etr_buf, offset,
                                   CORESIGHT_BARRIER_PKT_SIZE, &bufp);
-       if (WARN_ON(len < CORESIGHT_BARRIER_PKT_SIZE))
+       if (WARN_ON(len < 0 || len < CORESIGHT_BARRIER_PKT_SIZE))
                return -EINVAL;
        coresight_insert_barrier_packet(bufp);
        return offset + CORESIGHT_BARRIER_PKT_SIZE;