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From 907f100c841f39e37e4801f726f6b47c2aa9191f Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Tue, 6 Jul 2021 14:02:55 +1000
Subject: video/readers/png: Abort sooner if a read operation fails
Fuzzing revealed some inputs that were taking a long time, potentially
forever, because they did not bail quickly upon encountering an I/O error.
Try to catch I/O errors sooner and bail out.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/video/readers/png.c | 55 ++++++++++++++++++++++++++++++-----
1 file changed, 47 insertions(+), 8 deletions(-)
diff --git a/grub-core/video/readers/png.c b/grub-core/video/readers/png.c
index 0157ff742..e2a6b1cf3 100644
--- a/grub-core/video/readers/png.c
+++ b/grub-core/video/readers/png.c
@@ -142,6 +142,7 @@ static grub_uint8_t
grub_png_get_byte (struct grub_png_data *data)
{
grub_uint8_t r;
+ grub_ssize_t bytes_read = 0;
if ((data->inside_idat) && (data->idat_remain == 0))
{
@@ -175,7 +176,14 @@ grub_png_get_byte (struct grub_png_data *data)
}
r = 0;
- grub_file_read (data->file, &r, 1);
+ bytes_read = grub_file_read (data->file, &r, 1);
+
+ if (bytes_read != 1)
+ {
+ grub_error (GRUB_ERR_BAD_FILE_TYPE,
+ "png: unexpected end of data");
+ return 0;
+ }
if (data->inside_idat)
data->idat_remain--;
@@ -231,15 +239,16 @@ grub_png_decode_image_palette (struct grub_png_data *data,
if (len == 0)
return GRUB_ERR_NONE;
- for (i = 0; 3 * i < len && i < 256; i++)
+ grub_errno = GRUB_ERR_NONE;
+ for (i = 0; 3 * i < len && i < 256 && grub_errno == GRUB_ERR_NONE; i++)
for (j = 0; j < 3; j++)
data->palette[i][j] = grub_png_get_byte (data);
- for (i *= 3; i < len; i++)
+ for (i *= 3; i < len && grub_errno == GRUB_ERR_NONE; i++)
grub_png_get_byte (data);
grub_png_get_dword (data);
- return GRUB_ERR_NONE;
+ return grub_errno;
}
static grub_err_t
@@ -256,9 +265,13 @@ grub_png_decode_image_header (struct grub_png_data *data)
return grub_error (GRUB_ERR_BAD_FILE_TYPE, "png: invalid image size");
color_bits = grub_png_get_byte (data);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
data->is_16bit = (color_bits == 16);
color_type = grub_png_get_byte (data);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
/* According to PNG spec, no other types are valid. */
if ((color_type & ~(PNG_COLOR_MASK_ALPHA | PNG_COLOR_MASK_COLOR))
@@ -340,14 +353,20 @@ grub_png_decode_image_header (struct grub_png_data *data)
if (grub_png_get_byte (data) != PNG_COMPRESSION_BASE)
return grub_error (GRUB_ERR_BAD_FILE_TYPE,
"png: compression method not supported");
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
if (grub_png_get_byte (data) != PNG_FILTER_TYPE_BASE)
return grub_error (GRUB_ERR_BAD_FILE_TYPE,
"png: filter method not supported");
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
if (grub_png_get_byte (data) != PNG_INTERLACE_NONE)
return grub_error (GRUB_ERR_BAD_FILE_TYPE,
"png: interlace method not supported");
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
/* Skip crc checksum. */
grub_png_get_dword (data);
@@ -449,7 +468,7 @@ grub_png_get_huff_code (struct grub_png_data *data, struct huff_table *ht)
int code, i;
code = 0;
- for (i = 0; i < ht->max_length; i++)
+ for (i = 0; i < ht->max_length && grub_errno == GRUB_ERR_NONE; i++)
{
code = (code << 1) + grub_png_get_bits (data, 1);
if (code < ht->maxval[i])
@@ -504,8 +523,14 @@ grub_png_init_dynamic_block (struct grub_png_data *data)
grub_uint8_t lens[DEFLATE_HCLEN_MAX];
nl = DEFLATE_HLIT_BASE + grub_png_get_bits (data, 5);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
nd = DEFLATE_HDIST_BASE + grub_png_get_bits (data, 5);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
nb = DEFLATE_HCLEN_BASE + grub_png_get_bits (data, 4);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
if ((nl > DEFLATE_HLIT_MAX) || (nd > DEFLATE_HDIST_MAX) ||
(nb > DEFLATE_HCLEN_MAX))
@@ -533,7 +558,7 @@ grub_png_init_dynamic_block (struct grub_png_data *data)
data->dist_offset);
prev = 0;
- for (i = 0; i < nl + nd; i++)
+ for (i = 0; i < nl + nd && grub_errno == GRUB_ERR_NONE; i++)
{
int n, code;
struct huff_table *ht;
@@ -721,17 +746,21 @@ grub_png_read_dynamic_block (struct grub_png_data *data)
len = cplens[n];
if (cplext[n])
len += grub_png_get_bits (data, cplext[n]);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
n = grub_png_get_huff_code (data, &data->dist_table);
dist = cpdist[n];
if (cpdext[n])
dist += grub_png_get_bits (data, cpdext[n]);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
pos = data->wp - dist;
if (pos < 0)
pos += WSIZE;
- while (len > 0)
+ while (len > 0 && grub_errno == GRUB_ERR_NONE)
{
data->slide[data->wp] = data->slide[pos];
grub_png_output_byte (data, data->slide[data->wp]);
@@ -759,7 +788,11 @@ grub_png_decode_image_data (struct grub_png_data *data)
int final;
cmf = grub_png_get_byte (data);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
flg = grub_png_get_byte (data);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
if ((cmf & 0xF) != Z_DEFLATED)
return grub_error (GRUB_ERR_BAD_FILE_TYPE,
@@ -774,7 +807,11 @@ grub_png_decode_image_data (struct grub_png_data *data)
int block_type;
final = grub_png_get_bits (data, 1);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
block_type = grub_png_get_bits (data, 2);
+ if (grub_errno != GRUB_ERR_NONE)
+ return grub_errno;
switch (block_type)
{
@@ -790,7 +827,7 @@ grub_png_decode_image_data (struct grub_png_data *data)
grub_png_get_byte (data);
grub_png_get_byte (data);
- for (i = 0; i < len; i++)
+ for (i = 0; i < len && grub_errno == GRUB_ERR_NONE; i++)
grub_png_output_byte (data, grub_png_get_byte (data));
break;
@@ -1045,6 +1082,8 @@ grub_png_decode_png (struct grub_png_data *data)
len = grub_png_get_dword (data);
type = grub_png_get_dword (data);
+ if (grub_errno != GRUB_ERR_NONE)
+ break;
data->next_offset = data->file->offset + len + 4;
switch (type)
|
