xobs/simmel-bootloader
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Add static assert

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This guards against future increase in number of files
causing buffer overflow when reading the first root directory sector.
This commit is contained in:
Henry Gabryjelski 2019-03-13 15:20:42 -07:00
parent 4ea74d4600
commit c51a227fd9
1 changed files with 6 additions and 0 deletions
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6
src/usb/uf2/ghostfat.c
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@ -97,6 +97,11 @@ static struct TextFile const info[] = {
#define START_ROOTDIR (START_FAT1 + SECTORS_PER_FAT) #define START_ROOTDIR (START_FAT1 + SECTORS_PER_FAT)
#define START_CLUSTERS (START_ROOTDIR + ROOT_DIR_SECTORS) #define START_CLUSTERS (START_ROOTDIR + ROOT_DIR_SECTORS)
// all directory entries must fit in a single sector
// because otherwise current code overflows buffer
STATIC_ASSERT(NUM_INFO < (512 / sizeof(DirEntry)));
static FAT_BootBlock const BootBlock = { static FAT_BootBlock const BootBlock = {
.JumpInstruction = {0xeb, 0x3c, 0x90}, .JumpInstruction = {0xeb, 0x3c, 0x90},
.OEMInfo = "UF2 UF2 ", .OEMInfo = "UF2 UF2 ",
@ -198,6 +203,7 @@ void read_block(uint32_t block_no, uint8_t *data) {
((uint16_t *)(void *)data)[i] = v == UF2_LAST_SECTOR ? 0xffff : v + 1; ((uint16_t *)(void *)data)[i] = v == UF2_LAST_SECTOR ? 0xffff : v + 1;
} }
} else if (block_no < START_CLUSTERS) { } else if (block_no < START_CLUSTERS) {
// Use STATIC_ASSERT() above to ensure only first sector has entries
sectionIdx -= START_ROOTDIR; sectionIdx -= START_ROOTDIR;
if (sectionIdx == 0) { if (sectionIdx == 0) {
DirEntry *d = (void *)data; DirEntry *d = (void *)data;