| Message ID | 20231017-strncpy-drivers-net-wireless-broadcom-brcm80211-brcmfmac-cfg80211-c-v3-2-af780d74ae38@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | wifi: brcm80211: replace deprecated strncpy | expand |
On Tue, Oct 17, 2023 at 08:11:29PM +0000, Justin Stitt wrote: > Let's move away from using strncpy and instead use the more obvious > interface for this context. > > For wlc->pub->srom_ccode, we're just copying two bytes from ccode into > wlc->pub->srom_ccode with no expectation that srom_ccode be > NUL-terminated: > wlc->pub->srom_ccode is only used in regulatory_hint(): > 1193 | if (wl->pub->srom_ccode[0] && > 1194 | regulatory_hint(wl->wiphy, wl->pub->srom_ccode)) > 1195 | wiphy_err(wl->wiphy, "%s: regulatory hint failed\n", __func__); > > We can see that only index 0 and index 1 are accessed. > 3307 | int regulatory_hint(struct wiphy *wiphy, const char *alpha2) > 3308 | { > ... | ... > 3322 | request->alpha2[0] = alpha2[0]; > 3323 | request->alpha2[1] = alpha2[1]; > ... | ... > 3332 | } > > Since this is just a simple byte copy with correct lengths, let's use > memcpy(). There should be no functional change. > > In a similar boat, both wlc->country_default and > wlc->autocountry_default are just simple byte copies so let's use > memcpy. However, FWICT they aren't used anywhere. (they should be > used or removed -- not in scope of my patch, though). > > Signed-off-by: Justin Stitt <justinstitt@google.com> > --- > drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c > index 5a6d9c86552a..f6962e558d7c 100644 > --- a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c > +++ b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c > @@ -341,7 +341,7 @@ struct brcms_cm_info *brcms_c_channel_mgr_attach(struct brcms_c_info *wlc) > /* store the country code for passing up as a regulatory hint */ > wlc_cm->world_regd = brcms_world_regd(ccode, ccode_len); > if (brcms_c_country_valid(ccode)) > - strncpy(wlc->pub->srom_ccode, ccode, ccode_len); > + memcpy(wlc->pub->srom_ccode, ccode, ccode_len); const char *ccode = sprom->alpha2; int ccode_len = sizeof(sprom->alpha2); struct ssb_sprom { ... char alpha2[2]; /* Country Code as two chars like EU or US */ This should be marked __nonstring, IMO. struct brcms_pub { ... char srom_ccode[BRCM_CNTRY_BUF_SZ]; /* Country Code in SROM */ #define BRCM_CNTRY_BUF_SZ 4 /* Country string is 3 bytes + NUL */ This, however, is shown as explicitly %NUL terminated. The old strncpy wasn't %NUL terminating wlc->pub->srom_ccode, though, so the memcpy is the same result, but is that actually _correct_ here? > > /* > * If no custom world domain is found in the SROM, use the > @@ -354,10 +354,10 @@ struct brcms_cm_info *brcms_c_channel_mgr_attach(struct brcms_c_info *wlc) > } > > /* save default country for exiting 11d regulatory mode */ > - strncpy(wlc->country_default, ccode, ccode_len); > + memcpy(wlc->country_default, ccode, ccode_len); > > /* initialize autocountry_default to driver default */ > - strncpy(wlc->autocountry_default, ccode, ccode_len); > + memcpy(wlc->autocountry_default, ccode, ccode_len); struct brcms_c_info { ... char country_default[BRCM_CNTRY_BUF_SZ]; char autocountry_default[BRCM_CNTRY_BUF_SZ]; These are similar... So, this change results in the same behavior, but is it right? -Kees
On Wed, Oct 18, 2023 at 5:03 PM Kees Cook <keescook@chromium.org> wrote: > > On Tue, Oct 17, 2023 at 08:11:29PM +0000, Justin Stitt wrote: > > Let's move away from using strncpy and instead use the more obvious > > interface for this context. > > > > For wlc->pub->srom_ccode, we're just copying two bytes from ccode into > > wlc->pub->srom_ccode with no expectation that srom_ccode be > > NUL-terminated: > > wlc->pub->srom_ccode is only used in regulatory_hint(): > > 1193 | if (wl->pub->srom_ccode[0] && > > 1194 | regulatory_hint(wl->wiphy, wl->pub->srom_ccode)) > > 1195 | wiphy_err(wl->wiphy, "%s: regulatory hint failed\n", __func__); > > > > We can see that only index 0 and index 1 are accessed. > > 3307 | int regulatory_hint(struct wiphy *wiphy, const char *alpha2) > > 3308 | { > > ... | ... > > 3322 | request->alpha2[0] = alpha2[0]; > > 3323 | request->alpha2[1] = alpha2[1]; > > ... | ... > > 3332 | } > > > > Since this is just a simple byte copy with correct lengths, let's use > > memcpy(). There should be no functional change. > > > > In a similar boat, both wlc->country_default and > > wlc->autocountry_default are just simple byte copies so let's use > > memcpy. However, FWICT they aren't used anywhere. (they should be > > used or removed -- not in scope of my patch, though). > > > > Signed-off-by: Justin Stitt <justinstitt@google.com> > > --- > > drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c > > index 5a6d9c86552a..f6962e558d7c 100644 > > --- a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c > > +++ b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c > > @@ -341,7 +341,7 @@ struct brcms_cm_info *brcms_c_channel_mgr_attach(struct brcms_c_info *wlc) > > /* store the country code for passing up as a regulatory hint */ > > wlc_cm->world_regd = brcms_world_regd(ccode, ccode_len); > > if (brcms_c_country_valid(ccode)) > > - strncpy(wlc->pub->srom_ccode, ccode, ccode_len); > > + memcpy(wlc->pub->srom_ccode, ccode, ccode_len); > > const char *ccode = sprom->alpha2; > int ccode_len = sizeof(sprom->alpha2); > > struct ssb_sprom { > ... > char alpha2[2]; /* Country Code as two chars like EU or US */ > > This should be marked __nonstring, IMO. > > struct brcms_pub { > ... > char srom_ccode[BRCM_CNTRY_BUF_SZ]; /* Country Code in SROM */ > > #define BRCM_CNTRY_BUF_SZ 4 /* Country string is 3 bytes + NUL */ > > This, however, is shown as explicitly %NUL terminated. > > The old strncpy wasn't %NUL terminating wlc->pub->srom_ccode, though, so > the memcpy is the same result, but is that actually _correct_ here? Judging from the usage, we can see that only bytes at offset 0 and 1 are used. I think the comment "/* Country string is 3 bytes + NUL */" might be misleading or perhaps there are other uses that I can't find (which require NUL-termination)? > > > > > /* > > * If no custom world domain is found in the SROM, use the > > @@ -354,10 +354,10 @@ struct brcms_cm_info *brcms_c_channel_mgr_attach(struct brcms_c_info *wlc) > > } > > > > /* save default country for exiting 11d regulatory mode */ > > - strncpy(wlc->country_default, ccode, ccode_len); > > + memcpy(wlc->country_default, ccode, ccode_len); > > > > /* initialize autocountry_default to driver default */ > > - strncpy(wlc->autocountry_default, ccode, ccode_len); > > + memcpy(wlc->autocountry_default, ccode, ccode_len); > > struct brcms_c_info { > ... > char country_default[BRCM_CNTRY_BUF_SZ]; > char autocountry_default[BRCM_CNTRY_BUF_SZ]; > > These are similar... I can't find any uses for these either. > > So, this change results in the same behavior, but is it right? > > -Kees > > -- > Kees Cook Thanks Justin
On Wed, Oct 18, 2023 at 05:03:02PM -0700, Kees Cook wrote: > On Tue, Oct 17, 2023 at 08:11:29PM +0000, Justin Stitt wrote: > > Let's move away from using strncpy and instead use the more obvious > > interface for this context. > [...] > So, this change results in the same behavior ... I should have included my r-b tag: Reviewed-by: Kees Cook <keescook@chromium.org>
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c index 5a6d9c86552a..f6962e558d7c 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c @@ -341,7 +341,7 @@ struct brcms_cm_info *brcms_c_channel_mgr_attach(struct brcms_c_info *wlc) /* store the country code for passing up as a regulatory hint */ wlc_cm->world_regd = brcms_world_regd(ccode, ccode_len); if (brcms_c_country_valid(ccode)) - strncpy(wlc->pub->srom_ccode, ccode, ccode_len); + memcpy(wlc->pub->srom_ccode, ccode, ccode_len); /* * If no custom world domain is found in the SROM, use the @@ -354,10 +354,10 @@ struct brcms_cm_info *brcms_c_channel_mgr_attach(struct brcms_c_info *wlc) } /* save default country for exiting 11d regulatory mode */ - strncpy(wlc->country_default, ccode, ccode_len); + memcpy(wlc->country_default, ccode, ccode_len); /* initialize autocountry_default to driver default */ - strncpy(wlc->autocountry_default, ccode, ccode_len); + memcpy(wlc->autocountry_default, ccode, ccode_len); brcms_c_set_country(wlc_cm, wlc_cm->world_regd);
Let's move away from using strncpy and instead use the more obvious interface for this context. For wlc->pub->srom_ccode, we're just copying two bytes from ccode into wlc->pub->srom_ccode with no expectation that srom_ccode be NUL-terminated: wlc->pub->srom_ccode is only used in regulatory_hint(): 1193 | if (wl->pub->srom_ccode[0] && 1194 | regulatory_hint(wl->wiphy, wl->pub->srom_ccode)) 1195 | wiphy_err(wl->wiphy, "%s: regulatory hint failed\n", __func__); We can see that only index 0 and index 1 are accessed. 3307 | int regulatory_hint(struct wiphy *wiphy, const char *alpha2) 3308 | { ... | ... 3322 | request->alpha2[0] = alpha2[0]; 3323 | request->alpha2[1] = alpha2[1]; ... | ... 3332 | } Since this is just a simple byte copy with correct lengths, let's use memcpy(). There should be no functional change. In a similar boat, both wlc->country_default and wlc->autocountry_default are just simple byte copies so let's use memcpy. However, FWICT they aren't used anywhere. (they should be used or removed -- not in scope of my patch, though). Signed-off-by: Justin Stitt <justinstitt@google.com> --- drivers/net/wireless/broadcom/brcm80211/brcmsmac/channel.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)