From patchwork Fri Feb 16 19:27:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. 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R. Silva" To: Arend van Spriel , Kalle Valo , Nathan Chancellor Cc: linux-wireless@vger.kernel.org, brcm80211@lists.linux.dev, brcm80211-dev-list.pdl@broadcom.com, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH][next] wifi: brcmfmac: fweh: Fix boot crash on Raspberry Pi 4 Message-ID: Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Fix boot crash on Raspberry Pi by moving the update to `event->datalen` before data is copied into flexible-array member `data` via `memcpy()`. Flexible-array member `data` was annotated with `__counted_by(datalen)` in commit 62d19b358088 ("wifi: brcmfmac: fweh: Add __counted_by for struct brcmf_fweh_queue_item and use struct_size()"). The intention of this is to gain visibility into the size of `data` at run-time through its _counter_ (in this case `datalen`), and with this have its accesses bounds-checked at run-time via CONFIG_FORTIFY_SOURCE and CONFIG_UBSAN_BOUNDS. To effectively accomplish the above, we shall update the counter (`datalen`), before the first access to the flexible array (`data`), which was also done in the mentioned commit. However, commit edec42821911 ("wifi: brcmfmac: allow per-vendor event handling") inadvertently caused a buffer overflow, detected by FORTIFY_SOURCE. It moved the `event->datalen = datalen;` update to after the first `data` access, at which point `event->datalen` was not yet updated from zero (after calling `kzalloc()`), leading to the overflow issue. This fix repositions the `event->datalen = datalen;` update before accessing `data`, restoring the intended buffer overflow protection. :) Fixes: edec42821911 ("wifi: brcmfmac: allow per-vendor event handling") Reported-by: Nathan Chancellor Closes: https://gist.github.com/nathanchance/e22f681f3bfc467f15cdf6605021aaa6 Tested-by: Nathan Chancellor Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kees Cook Acked-by: Arend van Spriel --- drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c index 0774f6c59226..f0b6a7607f16 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c @@ -497,12 +497,12 @@ void brcmf_fweh_process_event(struct brcmf_pub *drvr, return; event->code = fwevt_idx; + event->datalen = datalen; event->ifidx = event_packet->msg.ifidx; /* use memcpy to get aligned event message */ memcpy(&event->emsg, &event_packet->msg, sizeof(event->emsg)); memcpy(event->data, data, datalen); - event->datalen = datalen; memcpy(event->ifaddr, event_packet->eth.h_dest, ETH_ALEN); brcmf_fweh_queue_event(fweh, event);