Hi Petri, > -----Original Message----- > From: Petri Gynther [mailto:pgynther@xxxxxxxxxx] > Sent: Tuesday, August 16, 2016 11:17 PM > To: linux-wireless@xxxxxxxxxxxxxxx > Cc: kvalo@xxxxxxxxxxxxxx; David Miller; Joe Perches; Amitkumar Karwar; > Petri Gynther > Subject: Re: [PATCH 2/2] mwifiex: fix unaligned read in > mwifiex_config_scan() > > On Fri, Aug 12, 2016 at 8:00 PM, Petri Gynther <pgynther@xxxxxxxxxx> > wrote: > > $ iwconfig mlan0 essid MySSID > > [ 36.930000] Path: /sbin/iwconfig > > [ 36.930000] CPU: 0 PID: 203 Comm: iwconfig Not tainted 4.7.0 #2 > > [ 36.940000] task: 866f83a0 ti: 866a6000 task.ti: 866a6000 > > [ 36.940000] > > [ECR ]: 0x00230400 => Misaligned r/w from 0x8677f403 > > [ 36.960000] [EFA ]: 0x8677f403 > > [ 36.960000] [BLINK ]: mwifiex_scan_networks+0x17a/0x198c [mwifiex] > > [ 36.960000] [ERET ]: mwifiex_scan_networks+0x18a/0x198c [mwifiex] > > [ 36.980000] [STAT32]: 0x00000206 : K E2 E1 > > [ 36.980000] BTA: 0x700736e2 SP: 0x866a7d0c FP: 0x5faddc84 > > [ 37.000000] LPS: 0x806a37ec LPE: 0x806a37fa LPC: 0x00000000 > > [ 37.000000] r00: 0x8677f401 r01: 0x8668aa08 r02: 0x00000001 > > r03: 0x00000000 r04: 0x8668b600 r05: 0x8677f406 > > r06: 0x8702b600 r07: 0x00000000 r08: 0x8702b600 > > r09: 0x00000000 r10: 0x870b3b00 r11: 0x00000000 > > r12: 0x00000000 > > [ 37.040000] > > [ 37.040000] Stack Trace: > > [ 37.040000] mwifiex_scan_networks+0x18a/0x198c [mwifiex] > > > > Root cause: > > mwifiex driver calls is_zero_ether_addr() against byte-aligned > address: > > > > drivers/net/wireless/marvell/mwifiex/fw.h: > > struct mwifiex_scan_cmd_config { > > /* > > * BSS mode to be sent in the firmware command > > */ > > u8 bss_mode; > > > > /* Specific BSSID used to filter scan results in the firmware > */ > > u8 specific_bssid[ETH_ALEN]; > > > > ... > > } __packed; > > > > drivers/net/wireless/marvell/mwifiex/scan.c: > > mwifiex_config_scan(..., struct mwifiex_scan_cmd_config *scan_cfg_out, > ...) > > ... > > if (adapter->ext_scan && > > !is_zero_ether_addr(scan_cfg_out->specific_bssid)) { > > ... > > } > > > > Since firmware-related struct mwifiex_scan_cmd_config cannot be > > changed, we need to use the new function > is_zero_ether_addr_unaligned() here. > > > > This is v2 of the original patch: > > [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses > > > > Per Joe's suggestion -- instead of modifying is_zero_ether_addr() -- > > add is_zero_ether_addr_unaligned() and use it where needed. > > > > Cc: Kalle Valo <kvalo@xxxxxxxxxxxxxx> > > Cc: David S. Miller <davem@xxxxxxxxxxxxx> > > Cc: Joe Perches <joe@xxxxxxxxxxx> > > Cc: Amitkumar Karwar <akarwar@xxxxxxxxxxx> > > Signed-off-by: Petri Gynther <pgynther@xxxxxxxxxx> > > --- > > drivers/net/wireless/marvell/mwifiex/scan.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c > > b/drivers/net/wireless/marvell/mwifiex/scan.c > > index bc5e52c..d648c88 100644 > > --- a/drivers/net/wireless/marvell/mwifiex/scan.c > > +++ b/drivers/net/wireless/marvell/mwifiex/scan.c > > @@ -883,7 +883,8 @@ mwifiex_config_scan(struct mwifiex_private *priv, > > sizeof(scan_cfg_out->specific_bssid)); > > > > if (adapter->ext_scan && > > - !is_zero_ether_addr(scan_cfg_out->specific_bssid)) > { > > + !is_zero_ether_addr_unaligned( > > + scan_cfg_out->specific_bssid)) { > > Any comments? Is this approach of adding > is_zero_ether_addr_unaligned() fine? We already have similar routine > ether_addr_equal_unaligned(). > > I don't see much benefit making a local, aligned copy here. It would > have to use memcpy w/ byte operations anyways and then still run > is_zero_ether_addr(). > > Amitkumar -- Is it possible to modify struct mwifiex_scan_cmd_config {} > and align specific_bssid field to u16 boundary? > We can’t change the structure. The reason is firmware at receiving end expects the variables in the same order. is_zero_ether_addr_unaligned() should be fine. Regards, Amitkumar
