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pngminus: Fix a buffer overflow in tokenizer
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@ctruta
ctruta committed Apr 11, 2019
1 parent a627bd2 commit 1f0221f
Showing 1 changed file with 26 additions and 25 deletions.
51 changes: 26 additions & 25 deletions contrib/pngminus/pnm2png.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
* 1.3 - 2017.08.24 - Fix potential overflow in buffer-size check
* (Glenn Randers-Pehrson)
* 1.4 - 2017.08.28 - Add PNGMINUS_UNUSED (Christian Hesse)
* 1.5 - 2018.08.05 - Fix buffer overflow in tokenizer (Cosmin Truta)
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby granted,
Expand Down Expand Up @@ -66,7 +67,7 @@ int main (int argc, char *argv[]);
void usage ();
BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
BOOL alpha);
void get_token(FILE *pnm_file, char *token);
void get_token(FILE *pnm_file, char *token_buf, size_t token_buf_size);
png_uint_32 get_data (FILE *pnm_file, int depth);
png_uint_32 get_value (FILE *pnm_file, int depth);

Expand Down Expand Up @@ -235,7 +236,7 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,

/* read header of PNM file */

get_token(pnm_file, type_token);
get_token(pnm_file, type_token, sizeof (type_token));
if (type_token[0] != 'P')
{
return FALSE;
Expand All @@ -245,10 +246,10 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
#if defined(PNG_WRITE_INVERT_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
raw = (type_token[1] == '4');
color_type = PNG_COLOR_TYPE_GRAY;
get_token(pnm_file, width_token);
get_token(pnm_file, width_token, sizeof (width_token));
sscanf (width_token, "%lu", &ul_width);
width = (png_uint_32) ul_width;
get_token(pnm_file, height_token);
get_token(pnm_file, height_token, sizeof (height_token));
sscanf (height_token, "%lu", &ul_height);
height = (png_uint_32) ul_height;
bit_depth = 1;
Expand All @@ -262,13 +263,13 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
{
raw = (type_token[1] == '5');
color_type = PNG_COLOR_TYPE_GRAY;
get_token(pnm_file, width_token);
get_token(pnm_file, width_token, sizeof (width_token));
sscanf (width_token, "%lu", &ul_width);
width = (png_uint_32) ul_width;
get_token(pnm_file, height_token);
get_token(pnm_file, height_token, sizeof (height_token));
sscanf (height_token, "%lu", &ul_height);
height = (png_uint_32) ul_height;
get_token(pnm_file, maxval_token);
get_token(pnm_file, maxval_token, sizeof (maxval_token));
sscanf (maxval_token, "%lu", &ul_maxval);
maxval = (png_uint_32) ul_maxval;

Expand All @@ -287,13 +288,13 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
{
raw = (type_token[1] == '6');
color_type = PNG_COLOR_TYPE_RGB;
get_token(pnm_file, width_token);
get_token(pnm_file, width_token, sizeof (width_token));
sscanf (width_token, "%lu", &ul_width);
width = (png_uint_32) ul_width;
get_token(pnm_file, height_token);
get_token(pnm_file, height_token, sizeof (height_token));
sscanf (height_token, "%lu", &ul_height);
height = (png_uint_32) ul_height;
get_token(pnm_file, maxval_token);
get_token(pnm_file, maxval_token, sizeof (maxval_token));
sscanf (maxval_token, "%lu", &ul_maxval);
maxval = (png_uint_32) ul_maxval;
if (maxval <= 1)
Expand Down Expand Up @@ -321,25 +322,25 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
if (color_type == PNG_COLOR_TYPE_RGB)
color_type = PNG_COLOR_TYPE_RGB_ALPHA;

get_token(alpha_file, type_token);
get_token(alpha_file, type_token, sizeof (type_token));
if (type_token[0] != 'P')
{
return FALSE;
}
else if ((type_token[1] == '2') || (type_token[1] == '5'))
{
alpha_raw = (type_token[1] == '5');
get_token(alpha_file, width_token);
get_token(alpha_file, width_token, sizeof (width_token));
sscanf (width_token, "%lu", &ul_alpha_width);
alpha_width=(png_uint_32) ul_alpha_width;
if (alpha_width != width)
return FALSE;
get_token(alpha_file, height_token);
get_token(alpha_file, height_token, sizeof (height_token));
sscanf (height_token, "%lu", &ul_alpha_height);
alpha_height = (png_uint_32) ul_alpha_height;
if (alpha_height != height)
return FALSE;
get_token(alpha_file, maxval_token);
get_token(alpha_file, maxval_token, sizeof (maxval_token));
sscanf (maxval_token, "%lu", &ul_maxval);
maxval = (png_uint_32) ul_maxval;
if (maxval <= 1)
Expand Down Expand Up @@ -532,9 +533,9 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
* get_token() - gets the first string after whitespace
*/

void get_token(FILE *pnm_file, char *token)
void get_token(FILE *pnm_file, char *token_buf, size_t token_buf_size)
{
int i = 0;
size_t i = 0;
int ret;

/* remove white-space and comment lines */
Expand All @@ -551,21 +552,21 @@ void get_token(FILE *pnm_file, char *token)
while ((ret != '\n') && (ret != '\r') && (ret != EOF));
}
if (ret == EOF) break;
token[i] = (unsigned char) ret;
token_buf[i] = (char) ret;
}
while ((token[i] == '\n') || (token[i] == '\r') || (token[i] == ' '));
while ((ret == '\n') || (ret == '\r') || (ret == ' '));

/* read string */
do
{
ret = fgetc(pnm_file);
if (ret == EOF) break;
i++;
token[i] = (unsigned char) ret;
if (++i == token_buf_size - 1) break;
token_buf[i] = (char) ret;
}
while ((token[i] != '\n') && (token[i] != '\r') && (token[i] != ' '));
while ((ret != '\n') && (ret != '\r') && (ret != ' '));

token[i] = '\0';
token_buf[i] = '\0';

return;
}
Expand Down Expand Up @@ -612,7 +613,7 @@ png_uint_32 get_data (FILE *pnm_file, int depth)
png_uint_32 get_value (FILE *pnm_file, int depth)
{
static png_uint_32 mask = 0;
png_byte token[16];
char token[16];
unsigned long ul_ret_value;
png_uint_32 ret_value;
int i = 0;
Expand All @@ -621,8 +622,8 @@ png_uint_32 get_value (FILE *pnm_file, int depth)
for (i = 0; i < depth; i++)
mask = (mask << 1) | 0x01;

get_token (pnm_file, (char *) token);
sscanf ((const char *) token, "%lu", &ul_ret_value);
get_token (pnm_file, token, sizeof (token));
sscanf (token, "%lu", &ul_ret_value);
ret_value = (png_uint_32) ul_ret_value;

ret_value &= mask;
Expand Down

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