Re: [PATCH 1/2] net/bnxt/tf_core: fix ignored return of EM delete

[Denis Sergeev <denserg.edu@gmail.com>]

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On 5/20/26 12:02 AM, Kishore Padmanabha wrote:
>
> On Tue, May 19, 2026 at 12:44 AM Denis Sergeev <denserg.edu@gmail.com> 
> wrote:
>
>     The return value of tfc_em_delete_raw() in tfc_em_delete() was
>     silently discarded: rc was unconditionally overwritten by the
>     subsequent tfc_cpm_get_cmm_inst() call without any error check.
>
>     If tfc_em_delete_raw() fails, the HW EM entry is not removed but
>     the function continues to free the corresponding SW pool entry,
>     creating a HW/SW state inconsistency that can lead to stale flow
>     matches or incorrect pool slot reuse.
>
>     Add an error check after the call and return -EINVAL on failure.
>
>     Found by Linux Verification Center (linuxtesting.org
>     <http://linuxtesting.org>) with SVACE.
>
>     Fixes: 80317ff6adfd ("net/bnxt/tf_core: support Thor2")
>     Cc: stable@dpdk.org
>
>     Signed-off-by: Denis Sergeev <denserg.edu@gmail.com>
>     ---
>      drivers/net/bnxt/tf_core/v3/tfc_em.c | 5 +++++
>      1 file changed, 5 insertions(+)
>
>     diff --git a/drivers/net/bnxt/tf_core/v3/tfc_em.c
>     b/drivers/net/bnxt/tf_core/v3/tfc_em.c
>     index 3fe4dbe3fe..4c126dc2f4 100644
>     --- a/drivers/net/bnxt/tf_core/v3/tfc_em.c
>     +++ b/drivers/net/bnxt/tf_core/v3/tfc_em.c
>     @@ -661,6 +661,11 @@ int tfc_em_delete(struct tfc *tfcp, struct
>     tfc_em_delete_parms *parms)
>                                    &db_offset
>      #endif
>                                    );
>     +       if (rc != 0) {
>     +               PMD_DRV_LOG_LINE(ERR, "tfc_em_delete_raw() failed:
>     %s",
>     +                                strerror(-rc));
>     +               return -EINVAL;
>     +       }
>
>             record_offset = REMOVE_POOL_FROM_OFFSET(pi.lkup_pool_sz_exp,
>     record_offset);
>
> This change is not required, even if deletion of the HW entry fails, 
> it should continue to delete the SW state, since at the end all the HW 
> entries are invalidated. Have you been able to reproduce a scenario 
> where this failure is seen.
>
>     -- 
>     2.50.1
>
Thanks for the review. I'll drop this patch.

The issue was flagged by a static analyzer that caught the discarded
return value of tfc_em_delete_raw(). Over the past week I tried to
reproduce an actual failure at runtime, but I couldn't. So it seems
this failure doesn't occur in real runtime.

-- 
Best regards,
Denis Sergeev

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