* Re: [PATCH] wifi: brcmfmac: Fix oops due to NULL pointer dereference in 'brcmf_sdiod_sglist_rw' [not found] ` <a2699327-0f86-4c70-8ca4-1225f3e712d1@broadcom.com> @ 2024-11-07 9:51 ` Kalle Valo 2024-11-07 11:28 ` Arend van Spriel 0 siblings, 1 reply; 2+ messages in thread From: Kalle Valo @ 2024-11-07 9:51 UTC (permalink / raw) To: Arend van Spriel Cc: Norbert van Bolhuis, linux-wireless, Norbert van Bolhuis, brcm80211 Arend van Spriel <arend.vanspriel@broadcom.com> writes: > On 11/7/2024 9:07 AM, Kalle Valo wrote: > >> Norbert van Bolhuis <nvbolhuis@gmail.com> writes: >> >>> This patch fixes a NULL pointer dereference bug in brcmfmac that occurs >>> when a high 'sd_sgentry_align' value applies (e.g. 512) and a lot of queued SKBs >>> are sent from the pkt queue. >>> >>> The problem is the number of entries in the pre-allocated sgtable, it is >>> nents = max(rxglom_size, txglom_size) + max(rxglom_size, txglom_size) >> 4 + 1. >>> Given the default [rt]xglom_size=32 it's actually 35 which is too small. >>> Worst case, the pkt queue can end up with 64 SKBs. This occurs when a new SKB >>> is added for each original SKB if tailroom isn't enough to hold tail_pad. >>> At least one sg entry is needed for each SKB. So, eventually the "skb_queue_walk loop" >>> in brcmf_sdiod_sglist_rw may run out of sg entries. This makes sg_next return >>> NULL and this causes the oops. >> BTW it would be good to fix (in a separate patch) the sg handling so >> that the kernel won't oops when sg entries rung. That's not really >> robust behaviour. >> >>> The patch sets nents to max(rxglom_size, txglom_size) * 2 to be able handle >>> the worst-case. >>> Btw. this requires only 64-35=29 * 16 (or 20 if CONFIG_NEED_SG_DMA_LENGTH) = 464 >>> additional bytes of memory. >> s-o-b missing, please read our documentation from the link below. > > I have not seen the actual patch. Which mailing list was it sent to? Only to linux-wireless, adding brcm80211 now. But the patch is in patchwork: https://patchwork.kernel.org/project/linux-wireless/patch/20241105204011.1603148-1-norbert.vanbolhuis@ev-box.com/ -- https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] wifi: brcmfmac: Fix oops due to NULL pointer dereference in 'brcmf_sdiod_sglist_rw' 2024-11-07 9:51 ` [PATCH] wifi: brcmfmac: Fix oops due to NULL pointer dereference in 'brcmf_sdiod_sglist_rw' Kalle Valo @ 2024-11-07 11:28 ` Arend van Spriel 0 siblings, 0 replies; 2+ messages in thread From: Arend van Spriel @ 2024-11-07 11:28 UTC (permalink / raw) To: Kalle Valo Cc: Norbert van Bolhuis, linux-wireless, Norbert van Bolhuis, brcm80211 On 11/7/2024 10:51 AM, Kalle Valo wrote: > Arend van Spriel <arend.vanspriel@broadcom.com> writes: > >> On 11/7/2024 9:07 AM, Kalle Valo wrote: >> >>> Norbert van Bolhuis <nvbolhuis@gmail.com> writes: >>> >>>> This patch fixes a NULL pointer dereference bug in brcmfmac that occurs >>>> when a high 'sd_sgentry_align' value applies (e.g. 512) and a lot of queued SKBs >>>> are sent from the pkt queue. >>>> >>>> The problem is the number of entries in the pre-allocated sgtable, it is >>>> nents = max(rxglom_size, txglom_size) + max(rxglom_size, txglom_size) >> 4 + 1. >>>> Given the default [rt]xglom_size=32 it's actually 35 which is too small. >>>> Worst case, the pkt queue can end up with 64 SKBs. This occurs when a new SKB >>>> is added for each original SKB if tailroom isn't enough to hold tail_pad. >>>> At least one sg entry is needed for each SKB. So, eventually the "skb_queue_walk loop" >>>> in brcmf_sdiod_sglist_rw may run out of sg entries. This makes sg_next return >>>> NULL and this causes the oops. >>> BTW it would be good to fix (in a separate patch) the sg handling so >>> that the kernel won't oops when sg entries rung. That's not really >>> robust behaviour. >>> >>>> The patch sets nents to max(rxglom_size, txglom_size) * 2 to be able handle >>>> the worst-case. >>>> Btw. this requires only 64-35=29 * 16 (or 20 if CONFIG_NEED_SG_DMA_LENGTH) = 464 >>>> additional bytes of memory. >>> s-o-b missing, please read our documentation from the link below. >> >> I have not seen the actual patch. Which mailing list was it sent to? > > Only to linux-wireless, adding brcm80211 now. But the patch is in > patchwork: > > https://patchwork.kernel.org/project/linux-wireless/patch/20241105204011.1603148-1-norbert.vanbolhuis@ev-box.com/ Thanks, Kalle I am also subscribed to linux-wireless, but search in thunderbird client did not come up with it. Thanks for the patchwork link. I should have checked that first. Gr. AvS ^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2024-11-07 11:28 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
[not found] <20241105204011.1603148-1-norbert.vanbolhuis@ev-box.com>
[not found] ` <87bjyrxy9r.fsf@kernel.org>
[not found] ` <a2699327-0f86-4c70-8ca4-1225f3e712d1@broadcom.com>
2024-11-07 9:51 ` [PATCH] wifi: brcmfmac: Fix oops due to NULL pointer dereference in 'brcmf_sdiod_sglist_rw' Kalle Valo
2024-11-07 11:28 ` Arend van Spriel
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox