Re: [PATCH 2/2] ath9k: fix ath_tx_process_buffer() potential null ptr dereference

On 2/17/21 12:30 AM, Kalle Valo wrote:

Shuah Khan [off-list ref] writes:

quoted

On 2/16/21 12:53 AM, Felix Fietkau wrote:

quoted

On 2021-02-16 08:03, Kalle Valo wrote:

quoted

Shuah Khan [off-list ref] wrote:

quoted

ath_tx_process_buffer() references ieee80211_find_sta_by_ifaddr()
return pointer (sta) outside null check. Fix it by moving the code
block under the null check.

This problem was found while reviewing code to debug RCU warn from
ath10k_wmi_tlv_parse_peer_stats_info() and a subsequent manual audit
of other callers of ieee80211_find_sta_by_ifaddr() that don't hold
RCU read lock.

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Kalle Valo <redacted>

Patch applied to ath-next branch of ath.git, thanks.

a56c14bb21b2 ath9k: fix ath_tx_process_buffer() potential null ptr dereference

I just took another look at this patch, and it is completely bogus.
Not only does the stated reason not make any sense (sta is simply passed
to other functions, not dereferenced without checks), but this also
introduces a horrible memory leak by skipping buffer completion if sta
is NULL.
Please drop it, the code is fine as-is.

A comment describing what you said here might be a good addition to this
comment block though.

Shuah, can you send a followup patch which reverts your change and adds
the comment? I try to avoid rebasing my trees.

I can do that.

thanks,
-- Shuah