In pflash_write() Coverity points out that we can decrement the
unsigned pfl->counter below zero, which makes it wrap around.  In
fact this is harmless, because if pfl->counter is 0 at this point we
also increment pfl->wcycle to 3, and the wcycle == 3 handling doesn't
look at counter; the only way back into code which looks at the
counter value is via wcycle == 1, which will reinitialize the counter.
But it's arguably a little clearer to break early in the "counter ==
0" if(), to avoid the decrement-below-zero.

Resolves: Coverity CID 1547611
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/block/pflash_cfi01.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
index c8f1cf5a872..2f3d1dd509c 100644
--- a/hw/block/pflash_cfi01.c
+++ b/hw/block/pflash_cfi01.c
@@ -614,6 +614,7 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset,
             if (!pfl->counter) {
                 trace_pflash_write(pfl->name, "block write finished");
                 pfl->wcycle++;
+                break;
             }
 
             pfl->counter--;
-- 
2.34.1

On 31/7/24 16:36, Peter Maydell wrote:
> In pflash_write() Coverity points out that we can decrement the
> unsigned pfl->counter below zero, which makes it wrap around.  In
> fact this is harmless, because if pfl->counter is 0 at this point we
> also increment pfl->wcycle to 3, and the wcycle == 3 handling doesn't
> look at counter; the only way back into code which looks at the
> counter value is via wcycle == 1, which will reinitialize the counter.
> But it's arguably a little clearer to break early in the "counter ==
> 0" if(), to avoid the decrement-below-zero.
> 
> Resolves: Coverity CID 1547611
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   hw/block/pflash_cfi01.c | 1 +
>   1 file changed, 1 insertion(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Am 31.07.2024 um 16:36 hat Peter Maydell geschrieben:
> In pflash_write() Coverity points out that we can decrement the
> unsigned pfl->counter below zero, which makes it wrap around.  In
> fact this is harmless, because if pfl->counter is 0 at this point we
> also increment pfl->wcycle to 3, and the wcycle == 3 handling doesn't
> look at counter; the only way back into code which looks at the
> counter value is via wcycle == 1, which will reinitialize the counter.
> But it's arguably a little clearer to break early in the "counter ==
> 0" if(), to avoid the decrement-below-zero.
> 
> Resolves: Coverity CID 1547611
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>