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drm/i915/bios: Validate LFP data table pointers

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Make sure the LFP data table pointers sane. Sensible looking
table entries, everything points correctly into the data block,
etc.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220405173410.11436-5-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Ville Syrjälä 2022-04-05 20:33:52 +03:00
parent 918f302596
commit 514003e142
1 changed files with 81 additions and 1 deletions
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82
drivers/gpu/drm/i915/display/intel_bios.c
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@ -133,6 +133,18 @@ static u32 block_offset(const void *bdb, enum bdb_block_id section_id)
return block - bdb;
}
/* size of the block excluding the header */
static u32 block_size(const void *bdb, enum bdb_block_id section_id)
{
const void *block;
block = find_raw_section(bdb, section_id);
if (!block)
return 0;
return get_blocksize(block);
}
struct bdb_block_entry {
struct list_head node;
enum bdb_block_id section_id;
@ -191,6 +203,74 @@ static const struct {
.min_size = sizeof(struct bdb_generic_dtd), },
};
static bool validate_lfp_data_ptrs(const void *bdb,
const struct bdb_lvds_lfp_data_ptrs *ptrs)
{
int fp_timing_size, dvo_timing_size, panel_pnp_id_size;
int data_block_size, lfp_data_size;
int i;
data_block_size = block_size(bdb, BDB_LVDS_LFP_DATA);
if (data_block_size == 0)
return false;
/* always 3 indicating the presence of fp_timing+dvo_timing+panel_pnp_id */
if (ptrs->lvds_entries != 3)
return false;
fp_timing_size = ptrs->ptr[0].fp_timing.table_size;
dvo_timing_size = ptrs->ptr[0].dvo_timing.table_size;
panel_pnp_id_size = ptrs->ptr[0].panel_pnp_id.table_size;
/* fp_timing has variable size */
if (fp_timing_size < 32 ||
dvo_timing_size != sizeof(struct lvds_dvo_timing) ||
panel_pnp_id_size != sizeof(struct lvds_pnp_id))
return false;
lfp_data_size = ptrs->ptr[1].fp_timing.offset - ptrs->ptr[0].fp_timing.offset;
if (16 * lfp_data_size > data_block_size)
return false;
/*
* Except for vlv/chv machines all real VBTs seem to have 6
* unaccounted bytes in the fp_timing table. And it doesn't
* appear to be a really intentional hole as the fp_timing
* 0xffff terminator is always within those 6 missing bytes.
*/
if (fp_timing_size + dvo_timing_size + panel_pnp_id_size != lfp_data_size &&
fp_timing_size + 6 + dvo_timing_size + panel_pnp_id_size != lfp_data_size)
return false;
if (ptrs->ptr[0].fp_timing.offset + fp_timing_size > ptrs->ptr[0].dvo_timing.offset ||
ptrs->ptr[0].dvo_timing.offset + dvo_timing_size != ptrs->ptr[0].panel_pnp_id.offset ||
ptrs->ptr[0].panel_pnp_id.offset + panel_pnp_id_size != lfp_data_size)
return false;
/* make sure the table entries have uniform size */
for (i = 1; i < 16; i++) {
if (ptrs->ptr[i].fp_timing.table_size != fp_timing_size ||
ptrs->ptr[i].dvo_timing.table_size != dvo_timing_size ||
ptrs->ptr[i].panel_pnp_id.table_size != panel_pnp_id_size)
return false;
if (ptrs->ptr[i].fp_timing.offset - ptrs->ptr[i-1].fp_timing.offset != lfp_data_size ||
ptrs->ptr[i].dvo_timing.offset - ptrs->ptr[i-1].dvo_timing.offset != lfp_data_size ||
ptrs->ptr[i].panel_pnp_id.offset - ptrs->ptr[i-1].panel_pnp_id.offset != lfp_data_size)
return false;
}
/* make sure the tables fit inside the data block */
for (i = 0; i < 16; i++) {
if (ptrs->ptr[i].fp_timing.offset + fp_timing_size > data_block_size ||
ptrs->ptr[i].dvo_timing.offset + dvo_timing_size > data_block_size ||
ptrs->ptr[i].panel_pnp_id.offset + panel_pnp_id_size > data_block_size)
return false;
}
return true;
}
/* make the data table offsets relative to the data block */
static bool fixup_lfp_data_ptrs(const void *bdb, void *ptrs_block)
{
@ -211,7 +291,7 @@ static bool fixup_lfp_data_ptrs(const void *bdb, void *ptrs_block)
ptrs->ptr[i].panel_pnp_id.offset -= offset;
}
return true;
return validate_lfp_data_ptrs(bdb, ptrs);
}
static void