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Modified lfs_ctz_extend to be a little bit safer

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Specifically around error handling. As is, incorrectly handled
errors could cause higher code to get uninitialized blocks,
potentially leading to writes to arbitray blocks on storage.
This commit is contained in:
Christopher Haster
2017-11-16 15:10:17 -06:00
parent 6664723e18
commit 2612e1b3fa
1 changed files with 16 additions and 12 deletions
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20
lfs.c
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@@ -1054,17 +1054,18 @@ static int lfs_ctz_find(lfs_t *lfs,
static int lfs_ctz_extend(lfs_t *lfs,
lfs_cache_t *rcache, lfs_cache_t *pcache,
lfs_block_t head, lfs_size_t size,
lfs_off_t *block, lfs_block_t *off) {
lfs_block_t *block, lfs_off_t *off) {
while (true) {
if (true) {
// go ahead and grab a block
int err = lfs_alloc(lfs, block);
lfs_block_t nblock;
int err = lfs_alloc(lfs, &nblock);
if (err) {
return err;
}
assert(*block >= 2 && *block <= lfs->cfg->block_count);
assert(nblock >= 2 && nblock <= lfs->cfg->block_count);
err = lfs_bd_erase(lfs, *block);
if (true) {
err = lfs_bd_erase(lfs, nblock);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
@@ -1073,6 +1074,7 @@ static int lfs_ctz_extend(lfs_t *lfs,
}
if (size == 0) {
*block = nblock;
*off = 0;
return 0;
}
@@ -1092,7 +1094,7 @@ static int lfs_ctz_extend(lfs_t *lfs,
}
err = lfs_cache_prog(lfs, pcache, rcache,
*block, i, &data, 1);
nblock, i, &data, 1);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
@@ -1101,6 +1103,7 @@ static int lfs_ctz_extend(lfs_t *lfs,
}
}
*block = nblock;
*off = size;
return 0;
}
@@ -1111,7 +1114,7 @@ static int lfs_ctz_extend(lfs_t *lfs,
for (lfs_off_t i = 0; i < skips; i++) {
int err = lfs_cache_prog(lfs, pcache, rcache,
*block, 4*i, &head, 4);
nblock, 4*i, &head, 4);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
@@ -1130,12 +1133,13 @@ static int lfs_ctz_extend(lfs_t *lfs,
assert(head >= 2 && head <= lfs->cfg->block_count);
}
*block = nblock;
*off = 4*skips;
return 0;
}
relocate:
LFS_DEBUG("Bad block at %d", *block);
LFS_DEBUG("Bad block at %d", nblock);
// just clear cache and try a new block
pcache->block = 0xffffffff;