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lib/os/mempool: Fix corruption case with block splitting #16966

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Merged
andrewboie merged 1 commit into from
Jun 26, 2019
Merged

lib/os/mempool: Fix corruption case with block splitting #16966

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24 changes: 19 additions & 5 deletions lib/os/mempool.c
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Original file line number Diff line number Diff line change
Expand Up @@ -72,9 +72,23 @@ static size_t buf_size(struct sys_mem_pool_base *p)
return p->n_max * p->max_sz;
}

static bool block_fits(struct sys_mem_pool_base *p, void *block, size_t bsz)
static bool block_fits(struct sys_mem_pool_base *p,
int lvl, int bn, size_t *lsizes)
{
return ((u8_t *)block + bsz - 1 - (u8_t *)p->buf) < buf_size(p);
u8_t *parent, *block_end;
size_t parent_sz;

block_end = (u8_t *)block_ptr(p, lsizes[lvl], bn) + lsizes[lvl];

if (lvl == 0) {
parent_sz = buf_size(p);
parent = p->buf;
} else {
parent_sz = lsizes[lvl - 1];
parent = block_ptr(p, lsizes[lvl - 1], bn / 4);
}

return block_end <= (parent + parent_sz);
}

void z_sys_mem_pool_base_init(struct sys_mem_pool_base *p)
Expand Down Expand Up @@ -161,7 +175,7 @@ static unsigned int bfree_recombine(struct sys_mem_pool_base *p, int level,
int i, lsz = lsizes[level];
void *block = block_ptr(p, lsz, bn);

__ASSERT(block_fits(p, block, lsz), "");
__ASSERT(block_fits(p, level, bn, lsizes), "");

/* Put it back */
set_free_bit(p, level, bn);
Expand All @@ -179,7 +193,7 @@ static unsigned int bfree_recombine(struct sys_mem_pool_base *p, int level,
for (i = 0; i < 4; i++) {
int b = (bn & ~3) + i;

if (block_fits(p, block_ptr(p, lsz, b), lsz)) {
if (block_fits(p, level, b, lsizes)) {
clear_free_bit(p, level, b);
sys_dlist_remove(block_ptr(p, lsz, b));
}
Expand Down Expand Up @@ -220,7 +234,7 @@ static void *block_break(struct sys_mem_pool_base *p, void *block, int l,
void *block2 = (lsz * i) + (char *)block;

set_free_bit(p, l + 1, lbn);
if (block_fits(p, block2, lsz)) {
if (block_fits(p, l + 1, lbn, lsizes)) {
sys_dlist_append(&p->levels[l + 1].free_list, block2);
}
}
Expand Down