* truncation in drivers/video/fbdev/neofb.c
@ 2023-08-29 16:45 Nick Desaulniers
2023-08-29 17:11 ` Helge Deller
0 siblings, 1 reply; 6+ messages in thread
From: Nick Desaulniers @ 2023-08-29 16:45 UTC (permalink / raw)
To: Helge Deller
Cc: linux-fbdev, dri-devel, clang-built-linux, LKML, Andrew Morton,
Nathan Chancellor
Helge,
A recent change in clang made it better about spotting snprintf that
will result in truncation. Nathan reported the following instances:
drivers/video/fbdev/neofb.c:1959:3: warning: 'snprintf' will always be
truncated; specified size is 16, but format string expands to at least
17 [-Wfortify-source]
drivers/video/fbdev/neofb.c:1963:3: warning: 'snprintf' will always be
truncated; specified size is 16, but format string expands to at least
18 [-Wfortify-source]
drivers/video/fbdev/neofb.c:1967:3: warning: 'snprintf' will always be
truncated; specified size is 16, but format string expands to at least
17 [-Wfortify-source]
drivers/video/fbdev/neofb.c:1971:3: warning: 'snprintf' will always be
truncated; specified size is 16, but format string expands to at least
17 [-Wfortify-source]
drivers/video/fbdev/neofb.c:1978:3: warning: 'snprintf' will always be
truncated; specified size is 16, but format string expands to at least
18 [-Wfortify-source]
drivers/video/fbdev/neofb.c:1985:3: warning: 'snprintf' will always be
truncated; specified size is 16, but format string expands to at least
17 [-Wfortify-source]
drivers/video/fbdev/neofb.c:1992:3: warning: 'snprintf' will always be
truncated; specified size is 16, but format string expands to at least
18 [-Wfortify-source]
https://github.com/ClangBuiltLinux/linux/issues/1923
Clang is right here. `info->fix.id` is declared as `char id[16];` so
indeed string literals like "MagicGraph 256AV+" indeed lead to
truncation. But this is declared in include/uapi/linux/fb.h; I assume
those headers cant be changed? Can the strings be shortened then? Is
it perhaps time to delete this driver?
I see AKPM mentioned alluded to this in
commit 0e90454 ("neofb: avoid overwriting fb_info fields")
(Also, snprintf probably isn't necessary for string literals that
don't contain format strings)
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: truncation in drivers/video/fbdev/neofb.c
2023-08-29 16:45 truncation in drivers/video/fbdev/neofb.c Nick Desaulniers
@ 2023-08-29 17:11 ` Helge Deller
2023-08-31 21:23 ` Helge Deller
0 siblings, 1 reply; 6+ messages in thread
From: Helge Deller @ 2023-08-29 17:11 UTC (permalink / raw)
To: Nick Desaulniers
Cc: linux-fbdev, dri-devel, clang-built-linux, LKML, Andrew Morton,
Nathan Chancellor
On 8/29/23 18:45, Nick Desaulniers wrote:
> Helge,
> A recent change in clang made it better about spotting snprintf that
> will result in truncation. Nathan reported the following instances:
>
> drivers/video/fbdev/neofb.c:1959:3: warning: 'snprintf' will always be
> truncated; specified size is 16, but format string expands to at least
> 17 [-Wfortify-source]
> drivers/video/fbdev/neofb.c:1963:3: warning: 'snprintf' will always be
> truncated; specified size is 16, but format string expands to at least
> 18 [-Wfortify-source]
> drivers/video/fbdev/neofb.c:1967:3: warning: 'snprintf' will always be
> truncated; specified size is 16, but format string expands to at least
> 17 [-Wfortify-source]
> drivers/video/fbdev/neofb.c:1971:3: warning: 'snprintf' will always be
> truncated; specified size is 16, but format string expands to at least
> 17 [-Wfortify-source]
> drivers/video/fbdev/neofb.c:1978:3: warning: 'snprintf' will always be
> truncated; specified size is 16, but format string expands to at least
> 18 [-Wfortify-source]
> drivers/video/fbdev/neofb.c:1985:3: warning: 'snprintf' will always be
> truncated; specified size is 16, but format string expands to at least
> 17 [-Wfortify-source]
> drivers/video/fbdev/neofb.c:1992:3: warning: 'snprintf' will always be
> truncated; specified size is 16, but format string expands to at least
> 18 [-Wfortify-source]
>
> https://github.com/ClangBuiltLinux/linux/issues/1923
>
> Clang is right here. `info->fix.id` is declared as `char id[16];` so
> indeed string literals like "MagicGraph 256AV+" indeed lead to
> truncation. But this is declared in include/uapi/linux/fb.h; I assume
> those headers cant be changed? Can the strings be shortened then? Is
> it perhaps time to delete this driver?
>
> I see AKPM mentioned alluded to this in
> commit 0e90454 ("neofb: avoid overwriting fb_info fields")
>
> (Also, snprintf probably isn't necessary for string literals that
> don't contain format strings)
It's just an ID field, so I don't think we need the full name of the card.
So using strscpy() and shorten the name, e.g. "MagicGr. 256XL+"
instead of "MagicGraph 256XL+" is probably the most simple solution?
Anyone want to send a patch?
Helge
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: truncation in drivers/video/fbdev/neofb.c
2023-08-29 17:11 ` Helge Deller
@ 2023-08-31 21:23 ` Helge Deller
2023-08-31 21:41 ` Nick Desaulniers
0 siblings, 1 reply; 6+ messages in thread
From: Helge Deller @ 2023-08-31 21:23 UTC (permalink / raw)
To: Nick Desaulniers, linux-fbdev, dri-devel, clang-built-linux, LKML,
Andrew Morton, Nathan Chancellor
* Helge Deller <deller@gmx.de>:
> On 8/29/23 18:45, Nick Desaulniers wrote:
> > A recent change in clang made it better about spotting snprintf that
> > will result in truncation. Nathan reported the following instances:
> >
> > drivers/video/fbdev/neofb.c:1959:3: warning: 'snprintf' will always be
> > truncated; specified size is 16, but format string expands to at least
> > 17 [-Wfortify-source]
FYI, I've added the patch below to the fbdev for-next git tree.
Helge
From: Helge Deller <deller@gmx.de>
Subject: [PATCH] fbdev: neofb: Shorten Neomagic product name in info struct
Avoid those compiler warnings:
neofb.c:1959:3: warning: 'snprintf' will always be truncated;
specified size is 16, but format string expands to at least 17 [-Wfortify-source]
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/all/CAKwvOdn0xoVWjQ6ufM_rojtKb0f1i1hW-J_xYGfKDNFdHwaeHQ@mail.gmail.com/
Link: https://github.com/ClangBuiltLinux/linux/issues/1923
diff --git a/drivers/video/fbdev/neofb.c b/drivers/video/fbdev/neofb.c
index d2f622b4c372..b905fe93b525 100644
--- a/drivers/video/fbdev/neofb.c
+++ b/drivers/video/fbdev/neofb.c
@@ -1948,49 +1948,40 @@ static struct fb_info *neo_alloc_fb_info(struct pci_dev *dev,
switch (info->fix.accel) {
case FB_ACCEL_NEOMAGIC_NM2070:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128");
+ strscpy(info->fix.id, "MagicGraph128", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2090:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128V");
+ strscpy(info->fix.id, "MagicGraph128V", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2093:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128ZV");
+ strscpy(info->fix.id, "MagicGraph128ZV", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2097:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128ZV+");
+ strscpy(info->fix.id, "Mag.Graph128ZV+", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2160:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128XD");
+ strscpy(info->fix.id, "MagicGraph128XD", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2200:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 256AV");
+ strscpy(info->fix.id, "MagicGraph256AV", sizeof(info->fix.id));
info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
FBINFO_HWACCEL_COPYAREA |
FBINFO_HWACCEL_FILLRECT;
break;
case FB_ACCEL_NEOMAGIC_NM2230:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 256AV+");
+ strscpy(info->fix.id, "MagicGraph256AV+", sizeof(info->fix.id));
info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
FBINFO_HWACCEL_COPYAREA |
FBINFO_HWACCEL_FILLRECT;
break;
case FB_ACCEL_NEOMAGIC_NM2360:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 256ZX");
+ strscpy(info->fix.id, "MagicGraph256ZX", sizeof(info->fix.id));
info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
FBINFO_HWACCEL_COPYAREA |
FBINFO_HWACCEL_FILLRECT;
break;
case FB_ACCEL_NEOMAGIC_NM2380:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 256XL+");
+ strscpy(info->fix.id, "MagicGraph256XL+", sizeof(info->fix.id));
info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
FBINFO_HWACCEL_COPYAREA |
FBINFO_HWACCEL_FILLRECT;
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: truncation in drivers/video/fbdev/neofb.c
2023-08-31 21:23 ` Helge Deller
@ 2023-08-31 21:41 ` Nick Desaulniers
2023-08-31 22:15 ` Helge Deller
0 siblings, 1 reply; 6+ messages in thread
From: Nick Desaulniers @ 2023-08-31 21:41 UTC (permalink / raw)
To: Helge Deller
Cc: linux-fbdev, dri-devel, clang-built-linux, LKML, Andrew Morton,
Nathan Chancellor, Kees Cook, Justin Stitt
On Thu, Aug 31, 2023 at 2:23 PM Helge Deller <deller@gmx.de> wrote:
>
> * Helge Deller <deller@gmx.de>:
> > On 8/29/23 18:45, Nick Desaulniers wrote:
> > > A recent change in clang made it better about spotting snprintf that
> > > will result in truncation. Nathan reported the following instances:
> > >
> > > drivers/video/fbdev/neofb.c:1959:3: warning: 'snprintf' will always be
> > > truncated; specified size is 16, but format string expands to at least
> > > 17 [-Wfortify-source]
>
> FYI, I've added the patch below to the fbdev for-next git tree.
>
> Helge
>
> From: Helge Deller <deller@gmx.de>
> Subject: [PATCH] fbdev: neofb: Shorten Neomagic product name in info struct
>
> Avoid those compiler warnings:
> neofb.c:1959:3: warning: 'snprintf' will always be truncated;
> specified size is 16, but format string expands to at least 17 [-Wfortify-source]
>
> Signed-off-by: Helge Deller <deller@gmx.de>
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Nick Desaulniers <ndesaulniers@google.com>
> Link: https://lore.kernel.org/all/CAKwvOdn0xoVWjQ6ufM_rojtKb0f1i1hW-J_xYGfKDNFdHwaeHQ@mail.gmail.com/
> Link: https://github.com/ClangBuiltLinux/linux/issues/1923
This indeed makes the warning go away, but that's more so due to the
use of strscpy now rather than snprintf. That alone is a good change
but we still have definite truncation. See below:
>
> diff --git a/drivers/video/fbdev/neofb.c b/drivers/video/fbdev/neofb.c
> index d2f622b4c372..b905fe93b525 100644
> --- a/drivers/video/fbdev/neofb.c
> +++ b/drivers/video/fbdev/neofb.c
> @@ -1948,49 +1948,40 @@ static struct fb_info *neo_alloc_fb_info(struct pci_dev *dev,
>
> switch (info->fix.accel) {
> case FB_ACCEL_NEOMAGIC_NM2070:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128");
> + strscpy(info->fix.id, "MagicGraph128", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2090:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128V");
> + strscpy(info->fix.id, "MagicGraph128V", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2093:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128ZV");
> + strscpy(info->fix.id, "MagicGraph128ZV", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2097:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128ZV+");
> + strscpy(info->fix.id, "Mag.Graph128ZV+", sizeof(info->fix.id));
I see the Mag.Graph change here; I'm curious why MagicGraph256XL+
didn't need that, too?
MagicGraph128ZV+
MagicGraph256XL+
those look like the same number of characters; are they? Does this one
need the `.` change?
```
diff --git a/drivers/video/fbdev/neofb.c b/drivers/video/fbdev/neofb.c
index b905fe93b525..6b7836f7f809 100644
--- a/drivers/video/fbdev/neofb.c
+++ b/drivers/video/fbdev/neofb.c
@@ -1957,7 +1957,7 @@ static struct fb_info *neo_alloc_fb_info(struct
pci_dev *dev,
strscpy(info->fix.id, "MagicGraph128ZV", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2097:
- strscpy(info->fix.id, "Mag.Graph128ZV+", sizeof(info->fix.id));
+ strscpy(info->fix.id, "MagicGraph128ZV+", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2160:
strscpy(info->fix.id, "MagicGraph128XD", sizeof(info->fix.id));
```
Builds without error for me. Though I guess the compiler doesn't know
what strscpy is semantically.
Ah
MagicGraph128ZV+
MagicGraph256XL+
are both 17 characters. (16 literal characters + trailing NUL)
So MagicGraph256XL+ (and MagicGraph256AV+) below will fail to copy the
NUL from the source, then overwrite the `+` with NUL IIUC.
There's no ambiguity for MagicGraph256XL+, but now MagicGraph256AV+
would look like MagicGraph256AV which is another possible variant.
Then perhaps MagicGraph256XL+ MagicGraph256AV+ and below might need to change.
Sorry, initially it looked like a simple fix and I was ready to sign
off on it; I hope I'm mistaken. Thank you for the patch, but do
consider sending it to the ML for review before committing.
> break;
> case FB_ACCEL_NEOMAGIC_NM2160:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128XD");
> + strscpy(info->fix.id, "MagicGraph128XD", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2200:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 256AV");
> + strscpy(info->fix.id, "MagicGraph256AV", sizeof(info->fix.id));
> info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
> FBINFO_HWACCEL_COPYAREA |
> FBINFO_HWACCEL_FILLRECT;
> break;
> case FB_ACCEL_NEOMAGIC_NM2230:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 256AV+");
> + strscpy(info->fix.id, "MagicGraph256AV+", sizeof(info->fix.id));
> info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
> FBINFO_HWACCEL_COPYAREA |
> FBINFO_HWACCEL_FILLRECT;
> break;
> case FB_ACCEL_NEOMAGIC_NM2360:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 256ZX");
> + strscpy(info->fix.id, "MagicGraph256ZX", sizeof(info->fix.id));
> info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
> FBINFO_HWACCEL_COPYAREA |
> FBINFO_HWACCEL_FILLRECT;
> break;
> case FB_ACCEL_NEOMAGIC_NM2380:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 256XL+");
> + strscpy(info->fix.id, "MagicGraph256XL+", sizeof(info->fix.id));
> info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
> FBINFO_HWACCEL_COPYAREA |
> FBINFO_HWACCEL_FILLRECT;
--
Thanks,
~Nick Desaulniers
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: truncation in drivers/video/fbdev/neofb.c
2023-08-31 21:41 ` Nick Desaulniers
@ 2023-08-31 22:15 ` Helge Deller
2023-08-31 22:26 ` Nick Desaulniers
0 siblings, 1 reply; 6+ messages in thread
From: Helge Deller @ 2023-08-31 22:15 UTC (permalink / raw)
To: Nick Desaulniers
Cc: linux-fbdev, dri-devel, clang-built-linux, LKML, Andrew Morton,
Nathan Chancellor, Kees Cook, Justin Stitt
* Nick Desaulniers <ndesaulniers@google.com>:
> On Thu, Aug 31, 2023 at 2:23 PM Helge Deller <deller@gmx.de> wrote:
> >
> > * Helge Deller <deller@gmx.de>:
> > > On 8/29/23 18:45, Nick Desaulniers wrote:
> > > > A recent change in clang made it better about spotting snprintf that
> > > > will result in truncation. Nathan reported the following instances:
> > > >
> > > > drivers/video/fbdev/neofb.c:1959:3: warning: 'snprintf' will always be
> > > > truncated; specified size is 16, but format string expands to at least
> > > > 17 [-Wfortify-source]
> >
> > FYI, I've added the patch below to the fbdev for-next git tree.
> > [...]
>
> This indeed makes the warning go away, but that's more so due to the
> use of strscpy now rather than snprintf. That alone is a good change
> but we still have definite truncation. See below:
> [...]
Nick, thanks for your review and findings!
Now every string should be max. 15 chars (which fits with the trailing
NUL into the char[16] array).
Helge
Subject: [PATCH] fbdev: neofb: Shorten Neomagic product name in info struct
Avoid those compiler warnings:
neofb.c:1959:3: warning: 'snprintf' will always be truncated;
specified size is 16, but format string expands to at least 17 [-Wfortify-source]
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/all/CAKwvOdn0xoVWjQ6ufM_rojtKb0f1i1hW-J_xYGfKDNFdHwaeHQ@mail.gmail.com/
Link: https://github.com/ClangBuiltLinux/linux/issues/1923
diff --git a/drivers/video/fbdev/neofb.c b/drivers/video/fbdev/neofb.c
index d2f622b4c372..b58b11015c0c 100644
--- a/drivers/video/fbdev/neofb.c
+++ b/drivers/video/fbdev/neofb.c
@@ -1948,49 +1948,40 @@ static struct fb_info *neo_alloc_fb_info(struct pci_dev *dev,
switch (info->fix.accel) {
case FB_ACCEL_NEOMAGIC_NM2070:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128");
+ strscpy(info->fix.id, "MagicGraph128", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2090:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128V");
+ strscpy(info->fix.id, "MagicGraph128V", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2093:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128ZV");
+ strscpy(info->fix.id, "MagicGraph128ZV", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2097:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128ZV+");
+ strscpy(info->fix.id, "Mag.Graph128ZV+", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2160:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 128XD");
+ strscpy(info->fix.id, "MagicGraph128XD", sizeof(info->fix.id));
break;
case FB_ACCEL_NEOMAGIC_NM2200:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 256AV");
+ strscpy(info->fix.id, "MagicGraph256AV", sizeof(info->fix.id));
info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
FBINFO_HWACCEL_COPYAREA |
FBINFO_HWACCEL_FILLRECT;
break;
case FB_ACCEL_NEOMAGIC_NM2230:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 256AV+");
+ strscpy(info->fix.id, "Mag.Graph256AV+", sizeof(info->fix.id));
info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
FBINFO_HWACCEL_COPYAREA |
FBINFO_HWACCEL_FILLRECT;
break;
case FB_ACCEL_NEOMAGIC_NM2360:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 256ZX");
+ strscpy(info->fix.id, "MagicGraph256ZX", sizeof(info->fix.id));
info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
FBINFO_HWACCEL_COPYAREA |
FBINFO_HWACCEL_FILLRECT;
break;
case FB_ACCEL_NEOMAGIC_NM2380:
- snprintf(info->fix.id, sizeof(info->fix.id),
- "MagicGraph 256XL+");
+ strscpy(info->fix.id, "Mag.Graph256XL+", sizeof(info->fix.id));
info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
FBINFO_HWACCEL_COPYAREA |
FBINFO_HWACCEL_FILLRECT;
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: truncation in drivers/video/fbdev/neofb.c
2023-08-31 22:15 ` Helge Deller
@ 2023-08-31 22:26 ` Nick Desaulniers
0 siblings, 0 replies; 6+ messages in thread
From: Nick Desaulniers @ 2023-08-31 22:26 UTC (permalink / raw)
To: Helge Deller
Cc: linux-fbdev, dri-devel, clang-built-linux, LKML, Andrew Morton,
Nathan Chancellor, Kees Cook, Justin Stitt
On Thu, Aug 31, 2023 at 3:16 PM Helge Deller <deller@gmx.de> wrote:
>
> * Nick Desaulniers <ndesaulniers@google.com>:
> > On Thu, Aug 31, 2023 at 2:23 PM Helge Deller <deller@gmx.de> wrote:
> > >
> > > * Helge Deller <deller@gmx.de>:
> > > > On 8/29/23 18:45, Nick Desaulniers wrote:
> > > > > A recent change in clang made it better about spotting snprintf that
> > > > > will result in truncation. Nathan reported the following instances:
> > > > >
> > > > > drivers/video/fbdev/neofb.c:1959:3: warning: 'snprintf' will always be
> > > > > truncated; specified size is 16, but format string expands to at least
> > > > > 17 [-Wfortify-source]
> > >
> > > FYI, I've added the patch below to the fbdev for-next git tree.
> > > [...]
> >
> > This indeed makes the warning go away, but that's more so due to the
> > use of strscpy now rather than snprintf. That alone is a good change
> > but we still have definite truncation. See below:
> > [...]
>
> Nick, thanks for your review and findings!
> Now every string should be max. 15 chars (which fits with the trailing
> NUL into the char[16] array).
>
> Helge
>
>
> Subject: [PATCH] fbdev: neofb: Shorten Neomagic product name in info struct
>
> Avoid those compiler warnings:
> neofb.c:1959:3: warning: 'snprintf' will always be truncated;
> specified size is 16, but format string expands to at least 17 [-Wfortify-source]
>
> Signed-off-by: Helge Deller <deller@gmx.de>
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Nick Desaulniers <ndesaulniers@google.com>
> Link: https://lore.kernel.org/all/CAKwvOdn0xoVWjQ6ufM_rojtKb0f1i1hW-J_xYGfKDNFdHwaeHQ@mail.gmail.com/
> Link: https://github.com/ClangBuiltLinux/linux/issues/1923
ah yeah LGTM
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
>
> diff --git a/drivers/video/fbdev/neofb.c b/drivers/video/fbdev/neofb.c
> index d2f622b4c372..b58b11015c0c 100644
> --- a/drivers/video/fbdev/neofb.c
> +++ b/drivers/video/fbdev/neofb.c
> @@ -1948,49 +1948,40 @@ static struct fb_info *neo_alloc_fb_info(struct pci_dev *dev,
>
> switch (info->fix.accel) {
> case FB_ACCEL_NEOMAGIC_NM2070:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128");
> + strscpy(info->fix.id, "MagicGraph128", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2090:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128V");
> + strscpy(info->fix.id, "MagicGraph128V", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2093:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128ZV");
> + strscpy(info->fix.id, "MagicGraph128ZV", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2097:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128ZV+");
> + strscpy(info->fix.id, "Mag.Graph128ZV+", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2160:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 128XD");
> + strscpy(info->fix.id, "MagicGraph128XD", sizeof(info->fix.id));
> break;
> case FB_ACCEL_NEOMAGIC_NM2200:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 256AV");
> + strscpy(info->fix.id, "MagicGraph256AV", sizeof(info->fix.id));
> info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
> FBINFO_HWACCEL_COPYAREA |
> FBINFO_HWACCEL_FILLRECT;
> break;
> case FB_ACCEL_NEOMAGIC_NM2230:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 256AV+");
> + strscpy(info->fix.id, "Mag.Graph256AV+", sizeof(info->fix.id));
> info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
> FBINFO_HWACCEL_COPYAREA |
> FBINFO_HWACCEL_FILLRECT;
> break;
> case FB_ACCEL_NEOMAGIC_NM2360:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 256ZX");
> + strscpy(info->fix.id, "MagicGraph256ZX", sizeof(info->fix.id));
> info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
> FBINFO_HWACCEL_COPYAREA |
> FBINFO_HWACCEL_FILLRECT;
> break;
> case FB_ACCEL_NEOMAGIC_NM2380:
> - snprintf(info->fix.id, sizeof(info->fix.id),
> - "MagicGraph 256XL+");
> + strscpy(info->fix.id, "Mag.Graph256XL+", sizeof(info->fix.id));
> info->flags |= FBINFO_HWACCEL_IMAGEBLIT |
> FBINFO_HWACCEL_COPYAREA |
> FBINFO_HWACCEL_FILLRECT;
>
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-08-31 22:27 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-08-29 16:45 truncation in drivers/video/fbdev/neofb.c Nick Desaulniers
2023-08-29 17:11 ` Helge Deller
2023-08-31 21:23 ` Helge Deller
2023-08-31 21:41 ` Nick Desaulniers
2023-08-31 22:15 ` Helge Deller
2023-08-31 22:26 ` Nick Desaulniers
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