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pngcp bug fixes

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The fixed size buffer for the file name being processed could have a byte
written beyond the end; a bug where the test was updated without changing the
size of the buffer.  This commit reduces the buffer to the system maximum.

png_getrowbytes could, in theory, return 0; probably only if there is a bug in
libpng but the code now checks.

Signed-off-by: John Bowler <jbowler@acm.org>
This commit is contained in:
John Bowler 2016-07-03 12:48:11 -07:00
parent 80495124b2
commit cfc19ff1b6
1 changed files with 11 additions and 4 deletions
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15
contrib/tools/pngcp.c
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@ -475,7 +475,7 @@ struct display
char curr[32*SL]; /* current options being tested */
char best[32*SL]; /* best options */
char namebuf[FILENAME_MAX+1]; /* output file name */
char namebuf[FILENAME_MAX]; /* output file name */
};
static void
@ -1639,7 +1639,7 @@ makename(struct display *dp, const char *dir, const char *infile)
{
size_t dsize = strlen(dir);
if (dsize < FILENAME_MAX+2)
if (dsize <= (sizeof dp->namebuf)-2) /* Allow for name + '/' + '\0' */
{
size_t isize = strlen(infile);
size_t istart = isize-1;
@ -1659,7 +1659,7 @@ makename(struct display *dp, const char *dir, const char *infile)
isize -= istart;
infile += istart;
if (dsize+isize <= FILENAME_MAX)
if (dsize+isize < (sizeof dp->namebuf)) /* dsize + infile + '\0' */
{
memcpy(dp->namebuf+dsize, infile, isize+1);
@ -1670,7 +1670,7 @@ makename(struct display *dp, const char *dir, const char *infile)
else
{
dp->namebuf[dsize] = 0;
dp->namebuf[dsize] = 0; /* allowed for: -2 at start */
display_log(dp, USER_ERROR, "%s%s: output file name too long",
dp->namebuf, infile);
}
@ -1799,8 +1799,15 @@ read_png(struct display *dp, const char *filename)
dp->bpp = png_get_bit_depth(dp->read_pp, dp->ip) *
png_get_channels(dp->read_pp, dp->ip);
{
/* png_get_rowbytes should never return 0 because the value is set by the
* first call to png_set_IHDR, which should have happened by now, but just
* in case:
*/
png_alloc_size_t rb = png_get_rowbytes(dp->read_pp, dp->ip);
if (rb == 0)
png_error(dp->read_pp, "invalid row byte count from libpng");
/* The size calc can overflow. */
if ((MAX_SIZE-dp->h)/rb < dp->h)
png_error(dp->read_pp, "image too large");