From: Rafał Miłecki rafal@milecki.pl

Keeping interrupts on could result in brcmfmac freeing some resources and then IRQ handlers trying to use them. That was obviously a straight path for crashing a kernel.

Example: CPU0 CPU1 ---- ---- brcmf_pcie_reset brcmf_pcie_bus_console_read brcmf_detach ... brcmf_fweh_detach brcmf_proto_detach brcmf_pcie_isr_thread ... brcmf_proto_msgbuf_rx_trigger ... drvr->proto->pd brcmf_pcie_release_irq

[ 363.789218] Unable to handle kernel NULL pointer dereference at virtual address 00000038 [ 363.797339] pgd = c0004000 [ 363.800050] [00000038] *pgd=00000000 [ 363.803635] Internal error: Oops: 17 [#1] SMP ARM (...) [ 364.029209] Backtrace: [ 364.031725] [<bf243838>] (brcmf_proto_msgbuf_rx_trigger [brcmfmac]) from [<bf2471dc>] (brcmf_pcie_isr_thread+0x228/0x274 [brcmfmac]) [ 364.043662] r7:00000001 r6:c8ca0000 r5:00010000 r4:c7b4f800

Fixes: 4684997d9eea ("brcmfmac: reset PCIe bus on a firmware crash") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Rafał Miłecki rafal@milecki.pl --- Kalle: if you are planning another pull request for 5.4 you may push this to the wireless-drivers. Otherwise make it wireless-drivers-next and lets have stable maintainers pick it. --- drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c index 3184dab41a5e..f64ce5074a55 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c @@ -1425,6 +1425,8 @@ static int brcmf_pcie_reset(struct device *dev) struct brcmf_fw_request *fwreq; int err;

+ brcmf_pcie_intr_disable(devinfo); + brcmf_pcie_bus_console_read(devinfo, true);

brcmf_detach(dev);