* Re: [PATCH] video/logo: protect against divide by zero when reading image [not found] <20210512054843.54883-1-yguoaz@gmail.com> @ 2021-05-12 12:03 ` Geert Uytterhoeven 2021-05-13 11:42 ` [PATCH v2] " Yiyuan GUO 0 siblings, 1 reply; 2+ messages in thread From: Geert Uytterhoeven @ 2021-05-12 12:03 UTC (permalink / raw) To: Yiyuan GUO; +Cc: Helge Deller, dri-devel, linux-parisc, linux-fbdev Hi Yiyuan, CC dri-devel, linux-fbdev On Wed, 12 May 2021, Yiyuan GUO wrote: > In video/logo/pnmtologo.c, the function read_image can read from the > image file an integer 0 and pass it to function get_number255, leading > to a divide by zero problem. > > Signed-off-by: Yiyuan GUO <yguoaz@gmail.com> Thanks for your patch! > --- a/drivers/video/logo/pnmtologo.c > +++ b/drivers/video/logo/pnmtologo.c > @@ -118,7 +118,12 @@ static unsigned int get_number(FILE *fp) > > static unsigned int get_number255(FILE *fp, unsigned int maxval) > { > - unsigned int val = get_number(fp); > + unsigned int val; > + > + if (!maxval) > + die("Corrupted maxval\n"); Please be consistent with other places reporting errors, e.g. die("%s: invalid maxval zero\n", filename); This looks like a strange place to check the validity of maxval. What about checking if right after its assignment? To avoid duplicating code, you can create a helper: static unsigned int get_maxval(FILE *fp) { unsigned int maxval = get_number(fp); if (!maxval) die("%s: invalid maxval zero\n", filename); return maxval; } and: /* Plain PGM */ - maxval = get_number(fp); + maxval = get_maxval(fp); and: /* Plain PPM */ - maxval = get_number(fp); + maxval = get_maxval(fp); > + > + val = get_number(fp); > return (255*val+maxval/2)/maxval; > } Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH v2] video/logo: protect against divide by zero when reading image 2021-05-12 12:03 ` [PATCH] video/logo: protect against divide by zero when reading image Geert Uytterhoeven @ 2021-05-13 11:42 ` Yiyuan GUO 0 siblings, 0 replies; 2+ messages in thread From: Yiyuan GUO @ 2021-05-13 11:42 UTC (permalink / raw) To: deller; +Cc: linux-fbdev, yguoaz, geert, dri-devel, linux-parisc In video/logo/pnmtologo.c, the function read_image can read from the image file an integer 0 and pass it to function get_number255, leading to a divide by zero problem. Signed-off-by: Yiyuan GUO <yguoaz@gmail.com> --- drivers/video/logo/pnmtologo.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/video/logo/pnmtologo.c b/drivers/video/logo/pnmtologo.c index 4718d7895..d9e8d1d5b 100644 --- a/drivers/video/logo/pnmtologo.c +++ b/drivers/video/logo/pnmtologo.c @@ -116,6 +116,16 @@ static unsigned int get_number(FILE *fp) return val; } +static unsigned int get_maxval(FILE *fp) +{ + unsigned int maxval = get_number(fp); + + if (!maxval) + die("%s: invalid maxval zero\n", filename); + + return maxval; +} + static unsigned int get_number255(FILE *fp, unsigned int maxval) { unsigned int val = get_number(fp); @@ -182,7 +192,7 @@ static void read_image(void) case '2': /* Plain PGM */ - maxval = get_number(fp); + maxval = get_maxval(fp); for (i = 0; i < logo_height; i++) for (j = 0; j < logo_width; j++) logo_data[i][j].red = logo_data[i][j].green = @@ -191,7 +201,7 @@ static void read_image(void) case '3': /* Plain PPM */ - maxval = get_number(fp); + maxval = get_maxval(fp); for (i = 0; i < logo_height; i++) for (j = 0; j < logo_width; j++) { logo_data[i][j].red = get_number255(fp, maxval); -- 2.25.1 ^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2021-05-14 7:32 UTC | newest] Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <20210512054843.54883-1-yguoaz@gmail.com> 2021-05-12 12:03 ` [PATCH] video/logo: protect against divide by zero when reading image Geert Uytterhoeven 2021-05-13 11:42 ` [PATCH v2] " Yiyuan GUO
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