From: Thomas Zimmermann <tzimmermann@suse.de> To: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: b.zolnierkie@samsung.com, gwan-gyeong.mun@intel.com, sam@ravnborg.org, daniel.vetter@ffwll.ch, bernard@vivo.com, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: Re: [PATCH] drivers/video: Fix -Wstringop-truncation in hdmi.c Date: Thu, 22 Oct 2020 09:01:52 +0200 [thread overview] Message-ID: <a07dff58-a6fa-8b3d-453a-a75bf47b5405@suse.de> (raw) In-Reply-To: <20201021230654.GS3942@pendragon.ideasonboard.com> Hi On 22.10.20 01:06, Laurent Pinchart wrote: > Hi Thomas, > > Thank you for the patch. > > On Wed, Oct 21, 2020 at 02:12:41PM +0200, Thomas Zimmermann wrote: >> Trying to copy into the string fields with strncpy() gives a warning from >> gcc. Both fields are part of a packed HDMI header and do not require a >> terminating \0 character. >> >> ../drivers/video/hdmi.c: In function 'hdmi_spd_infoframe_init': >> ../drivers/video/hdmi.c:230:2: warning: 'strncpy' specified bound 8 equals destination size [-Wstringop-truncation] >> 230 | strncpy(frame->vendor, vendor, sizeof(frame->vendor)); >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> ../drivers/video/hdmi.c:231:2: warning: 'strncpy' specified bound 16 equals destination size [-Wstringop-truncation] >> 231 | strncpy(frame->product, product, sizeof(frame->product)); >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> >> Just use memcpy() instead. >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >> --- >> drivers/video/hdmi.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c >> index b7a1d6fae90d..1e4cb63d0d11 100644 >> --- a/drivers/video/hdmi.c >> +++ b/drivers/video/hdmi.c >> @@ -221,14 +221,18 @@ EXPORT_SYMBOL(hdmi_avi_infoframe_pack); >> int hdmi_spd_infoframe_init(struct hdmi_spd_infoframe *frame, >> const char *vendor, const char *product) >> { >> + size_t len; >> + >> memset(frame, 0, sizeof(*frame)); >> >> frame->type = HDMI_INFOFRAME_TYPE_SPD; >> frame->version = 1; >> frame->length = HDMI_SPD_INFOFRAME_SIZE; >> >> - strncpy(frame->vendor, vendor, sizeof(frame->vendor)); >> - strncpy(frame->product, product, sizeof(frame->product)); >> + len = strlen(vendor); >> + memcpy(frame->vendor, vendor, min(len, sizeof(frame->vendor))); >> + len = strlen(product); >> + memcpy(frame->product, product, min(len, sizeof(frame->product))); > > As this seems to be a legitimate use of strncpy(), isn't there a way to > silence the warning without requiring this additional runtime complexity > ? Yes, the original code this correct. I looked through include/string.h if there's better string function, but none fits. Most of them 0-terminate the output string. The only simple fix seems to be to set gcc's -Wno-stringop-truncation here. I'd expect that would be an even less preferable change. Best regards Thomas > >> >> return 0; >> } > -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Zimmermann <tzimmermann@suse.de> To: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: linux-fbdev@vger.kernel.org, b.zolnierkie@samsung.com, bernard@vivo.com, dri-devel@lists.freedesktop.org, gwan-gyeong.mun@intel.com, daniel.vetter@ffwll.ch, sam@ravnborg.org Subject: Re: [PATCH] drivers/video: Fix -Wstringop-truncation in hdmi.c Date: Thu, 22 Oct 2020 09:01:52 +0200 [thread overview] Message-ID: <a07dff58-a6fa-8b3d-453a-a75bf47b5405@suse.de> (raw) In-Reply-To: <20201021230654.GS3942@pendragon.ideasonboard.com> Hi On 22.10.20 01:06, Laurent Pinchart wrote: > Hi Thomas, > > Thank you for the patch. > > On Wed, Oct 21, 2020 at 02:12:41PM +0200, Thomas Zimmermann wrote: >> Trying to copy into the string fields with strncpy() gives a warning from >> gcc. Both fields are part of a packed HDMI header and do not require a >> terminating \0 character. >> >> ../drivers/video/hdmi.c: In function 'hdmi_spd_infoframe_init': >> ../drivers/video/hdmi.c:230:2: warning: 'strncpy' specified bound 8 equals destination size [-Wstringop-truncation] >> 230 | strncpy(frame->vendor, vendor, sizeof(frame->vendor)); >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> ../drivers/video/hdmi.c:231:2: warning: 'strncpy' specified bound 16 equals destination size [-Wstringop-truncation] >> 231 | strncpy(frame->product, product, sizeof(frame->product)); >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> >> Just use memcpy() instead. >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >> --- >> drivers/video/hdmi.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c >> index b7a1d6fae90d..1e4cb63d0d11 100644 >> --- a/drivers/video/hdmi.c >> +++ b/drivers/video/hdmi.c >> @@ -221,14 +221,18 @@ EXPORT_SYMBOL(hdmi_avi_infoframe_pack); >> int hdmi_spd_infoframe_init(struct hdmi_spd_infoframe *frame, >> const char *vendor, const char *product) >> { >> + size_t len; >> + >> memset(frame, 0, sizeof(*frame)); >> >> frame->type = HDMI_INFOFRAME_TYPE_SPD; >> frame->version = 1; >> frame->length = HDMI_SPD_INFOFRAME_SIZE; >> >> - strncpy(frame->vendor, vendor, sizeof(frame->vendor)); >> - strncpy(frame->product, product, sizeof(frame->product)); >> + len = strlen(vendor); >> + memcpy(frame->vendor, vendor, min(len, sizeof(frame->vendor))); >> + len = strlen(product); >> + memcpy(frame->product, product, min(len, sizeof(frame->product))); > > As this seems to be a legitimate use of strncpy(), isn't there a way to > silence the warning without requiring this additional runtime complexity > ? Yes, the original code this correct. I looked through include/string.h if there's better string function, but none fits. Most of them 0-terminate the output string. The only simple fix seems to be to set gcc's -Wno-stringop-truncation here. I'd expect that would be an even less preferable change. Best regards Thomas > >> >> return 0; >> } > -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-10-22 7:01 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-21 12:12 [PATCH] drivers/video: Fix -Wstringop-truncation in hdmi.c Thomas Zimmermann 2020-10-21 12:12 ` Thomas Zimmermann 2020-10-21 23:06 ` Laurent Pinchart 2020-10-21 23:06 ` Laurent Pinchart 2020-10-22 7:01 ` Thomas Zimmermann [this message] 2020-10-22 7:01 ` Thomas Zimmermann 2020-11-01 9:50 ` Sam Ravnborg 2020-11-01 9:50 ` Sam Ravnborg 2020-11-01 16:43 ` Thomas Zimmermann 2020-11-01 16:43 ` Thomas Zimmermann
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