* [PATCH] drm/bridge: ti-sn65dsi86: Avoid possible buffer overflow @ 2023-06-06 7:55 Su Hui 2023-06-06 15:28 ` Doug Anderson 0 siblings, 1 reply; 4+ messages in thread From: Su Hui @ 2023-06-06 7:55 UTC (permalink / raw) To: Douglas Anderson, Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart, Jonas Karlman, Jernej Skrabec, David Airlie, Daniel Vetter Cc: u.kleine-koenig, andersson, dri-devel, linux-kernel, Su Hui Smatch error:buffer overflow 'ti_sn_bridge_refclk_lut' 5 <= 5. Fixes: cea86c5bb442 ("drm/bridge: ti-sn65dsi86: Implement the pwm_chip") Signed-off-by: Su Hui <suhui@nfschina.com> --- drivers/gpu/drm/bridge/ti-sn65dsi86.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index 7a748785c545..952aae4221e7 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -305,7 +305,8 @@ static void ti_sn_bridge_set_refclk_freq(struct ti_sn65dsi86 *pdata) * The PWM refclk is based on the value written to SN_DPPLL_SRC_REG, * regardless of its actual sourcing. */ - pdata->pwm_refclk_freq = ti_sn_bridge_refclk_lut[i]; + if (i < refclk_lut_size) + pdata->pwm_refclk_freq = ti_sn_bridge_refclk_lut[i]; } static void ti_sn65dsi86_enable_comms(struct ti_sn65dsi86 *pdata) -- 2.30.2 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/bridge: ti-sn65dsi86: Avoid possible buffer overflow 2023-06-06 7:55 [PATCH] drm/bridge: ti-sn65dsi86: Avoid possible buffer overflow Su Hui @ 2023-06-06 15:28 ` Doug Anderson 2023-06-07 0:50 ` Longsuhui 2023-06-07 1:17 ` Su Hui 0 siblings, 2 replies; 4+ messages in thread From: Doug Anderson @ 2023-06-06 15:28 UTC (permalink / raw) To: Su Hui Cc: Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart, Jonas Karlman, Jernej Skrabec, David Airlie, Daniel Vetter, andersson, linux-kernel, dri-devel, u.kleine-koenig Hi, On Tue, Jun 6, 2023 at 12:56 AM Su Hui <suhui@nfschina.com> wrote: > > Smatch error:buffer overflow 'ti_sn_bridge_refclk_lut' 5 <= 5. > > Fixes: cea86c5bb442 ("drm/bridge: ti-sn65dsi86: Implement the pwm_chip") > Signed-off-by: Su Hui <suhui@nfschina.com> > --- > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c > index 7a748785c545..952aae4221e7 100644 > --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c > @@ -305,7 +305,8 @@ static void ti_sn_bridge_set_refclk_freq(struct ti_sn65dsi86 *pdata) > * The PWM refclk is based on the value written to SN_DPPLL_SRC_REG, > * regardless of its actual sourcing. > */ > - pdata->pwm_refclk_freq = ti_sn_bridge_refclk_lut[i]; > + if (i < refclk_lut_size) > + pdata->pwm_refclk_freq = ti_sn_bridge_refclk_lut[i]; I don't think this is quite the right fix. I don't think we can just skip assigning "pdata->pwm_refclk_freq". In general I think we're in pretty bad shape if we ever fail to match a refclk from the table and I'm not quite sure how the bridge chip could work at all in this case. Probably that at least deserves a warning message in the logs. There's no place to return an error though, so I guess the warning is the best we can do and then we can do our best to do something reasonable. In this case, I think "reasonable" might be that if the for loop exits and "i == refclk_lut_size" that we should set "i" to 1. According to the datasheet [1] setting a value of 5 (which the existing code does) is the same as setting a value of 1 (the default) and if it's 1 then we'll be able to look this up in the table. [1] https://www.ti.com/lit/gpn/sn65dsi86 -Doug ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/bridge: ti-sn65dsi86: Avoid possible buffer overflow 2023-06-06 15:28 ` Doug Anderson @ 2023-06-07 0:50 ` Longsuhui 2023-06-07 1:17 ` Su Hui 1 sibling, 0 replies; 4+ messages in thread From: Longsuhui @ 2023-06-07 0:50 UTC (permalink / raw) To: Doug Anderson Cc: Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart, Jonas Karlman, Jernej Skrabec, David Airlie, Daniel Vetter, andersson, linux-kernel, dri-devel, u.kleine-koenig Hi, On 2023/6/6 23:28, Doug Anderson wrote: > Hi, > > On Tue, Jun 6, 2023 at 12:56 AM Su Hui <suhui@nfschina.com> wrote: >> Smatch error:buffer overflow 'ti_sn_bridge_refclk_lut' 5 <= 5. >> >> Fixes: cea86c5bb442 ("drm/bridge: ti-sn65dsi86: Implement the pwm_chip") >> Signed-off-by: Su Hui <suhui@nfschina.com> >> --- >> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> index 7a748785c545..952aae4221e7 100644 >> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> @@ -305,7 +305,8 @@ static void ti_sn_bridge_set_refclk_freq(struct ti_sn65dsi86 *pdata) >> * The PWM refclk is based on the value written to SN_DPPLL_SRC_REG, >> * regardless of its actual sourcing. >> */ >> - pdata->pwm_refclk_freq = ti_sn_bridge_refclk_lut[i]; >> + if (i < refclk_lut_size) >> + pdata->pwm_refclk_freq = ti_sn_bridge_refclk_lut[i]; > I don't think this is quite the right fix. I don't think we can just > skip assigning "pdata->pwm_refclk_freq". In general I think we're in > pretty bad shape if we ever fail to match a refclk from the table and > I'm not quite sure how the bridge chip could work at all in this case. > Probably that at least deserves a warning message in the logs. There's > no place to return an error though, so I guess the warning is the best > we can do and then we can do our best to do something reasonable. > > In this case, I think "reasonable" might be that if the for loop exits > and "i == refclk_lut_size" that we should set "i" to 1. According to > the datasheet [1] setting a value of 5 (which the existing code does) > is the same as setting a value of 1 (the default) and if it's 1 then > we'll be able to look this up in the table. I think you are right. And " if ( i >= refclk_lut_size) i=1" is a suitable change. I will send patch v2 a litter latter. Thanks for your suggestion. Su Hui > > [1] https://www.ti.com/lit/gpn/sn65dsi86 > > -Doug ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/bridge: ti-sn65dsi86: Avoid possible buffer overflow 2023-06-06 15:28 ` Doug Anderson 2023-06-07 0:50 ` Longsuhui @ 2023-06-07 1:17 ` Su Hui 1 sibling, 0 replies; 4+ messages in thread From: Su Hui @ 2023-06-07 1:17 UTC (permalink / raw) To: Doug Anderson Cc: Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart, Jonas Karlman, Jernej Skrabec, David Airlie, Daniel Vetter, andersson, linux-kernel, dri-devel, u.kleine-koenig Hi, On 2023/6/6 23:28, Doug Anderson wrote: > Hi, > > On Tue, Jun 6, 2023 at 12:56 AM Su Hui <suhui@nfschina.com> wrote: >> Smatch error:buffer overflow 'ti_sn_bridge_refclk_lut' 5 <= 5. >> >> Fixes: cea86c5bb442 ("drm/bridge: ti-sn65dsi86: Implement the pwm_chip") >> Signed-off-by: Su Hui <suhui@nfschina.com> >> --- >> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> index 7a748785c545..952aae4221e7 100644 >> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> @@ -305,7 +305,8 @@ static void ti_sn_bridge_set_refclk_freq(struct ti_sn65dsi86 *pdata) >> * The PWM refclk is based on the value written to SN_DPPLL_SRC_REG, >> * regardless of its actual sourcing. >> */ >> - pdata->pwm_refclk_freq = ti_sn_bridge_refclk_lut[i]; >> + if (i < refclk_lut_size) >> + pdata->pwm_refclk_freq = ti_sn_bridge_refclk_lut[i]; > I don't think this is quite the right fix. I don't think we can just > skip assigning "pdata->pwm_refclk_freq". In general I think we're in > pretty bad shape if we ever fail to match a refclk from the table and > I'm not quite sure how the bridge chip could work at all in this case. > Probably that at least deserves a warning message in the logs. There's > no place to return an error though, so I guess the warning is the best > we can do and then we can do our best to do something reasonable. > > In this case, I think "reasonable" might be that if the for loop exits > and "i == refclk_lut_size" that we should set "i" to 1. According to > the datasheet [1] setting a value of 5 (which the existing code does) > is the same as setting a value of 1 (the default) and if it's 1 then > we'll be able to look this up in the table. I think you are right, set i to 1 if i >= refclk_lut_size. I will resend this patch soon. Thanks for your reply! Su Hui > > [1] https://www.ti.com/lit/gpn/sn65dsi86 > > -Doug ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-06-07 1:17 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-06-06 7:55 [PATCH] drm/bridge: ti-sn65dsi86: Avoid possible buffer overflow Su Hui 2023-06-06 15:28 ` Doug Anderson 2023-06-07 0:50 ` Longsuhui 2023-06-07 1:17 ` Su Hui
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