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author | David Gibson <david@gibson.dropbear.id.au> | 2021-06-08 15:17:11 +1000 |
---|---|---|
committer | David Gibson <david@gibson.dropbear.id.au> | 2021-06-08 15:17:11 +1000 |
commit | 4c2ef8f4d14ca411b41b9c6891028d58d2079bf7 (patch) | |
tree | 620618e13ceda692202d9ae02ddfae0488a68a93 | |
parent | e59ca36fb70e32f8b4850135ab94fdf44cd22557 (diff) | |
download | dtc-4c2ef8f4d14ca411b41b9c6891028d58d2079bf7.tar.gz |
checks: Introduce is_multiple_of()
In a number of places we check if one number is a multiple of another,
using a modulus. In some of those cases the divisor is potentially zero,
which needs special handling or we could trigger a divide by zero.
Introduce an is_multiple_of() helper to safely handle this case, and use
it in a bunch of places. This should close Coverity issue 1501687, maybe
others as well.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
-rw-r--r-- | checks.c | 18 |
1 files changed, 13 insertions, 5 deletions
@@ -143,6 +143,14 @@ static void check_nodes_props(struct check *c, struct dt_info *dti, struct node check_nodes_props(c, dti, child); } +static bool is_multiple_of(int multiple, int divisor) +{ + if (divisor == 0) + return multiple == 0; + else + return (multiple % divisor) == 0; +} + static bool run_check(struct check *c, struct dt_info *dti) { struct node *dt = dti->dt; @@ -766,7 +774,7 @@ static void check_reg_format(struct check *c, struct dt_info *dti, size_cells = node_size_cells(node->parent); entrylen = (addr_cells + size_cells) * sizeof(cell_t); - if (!entrylen || (prop->val.len % entrylen) != 0) + if (!is_multiple_of(prop->val.len, entrylen)) FAIL_PROP(c, dti, node, prop, "property has invalid length (%d bytes) " "(#address-cells == %d, #size-cells == %d)", prop->val.len, addr_cells, size_cells); @@ -807,7 +815,7 @@ static void check_ranges_format(struct check *c, struct dt_info *dti, "#size-cells (%d) differs from %s (%d)", ranges, c_size_cells, node->parent->fullpath, p_size_cells); - } else if ((prop->val.len % entrylen) != 0) { + } else if (!is_multiple_of(prop->val.len, entrylen)) { FAIL_PROP(c, dti, node, prop, "\"%s\" property has invalid length (%d bytes) " "(parent #address-cells == %d, child #address-cells == %d, " "#size-cells == %d)", ranges, prop->val.len, @@ -1382,7 +1390,7 @@ static void check_property_phandle_args(struct check *c, struct node *root = dti->dt; int cell, cellsize = 0; - if (prop->val.len % sizeof(cell_t)) { + if (!is_multiple_of(prop->val.len, sizeof(cell_t))) { FAIL_PROP(c, dti, node, prop, "property size (%d) is invalid, expected multiple of %zu", prop->val.len, sizeof(cell_t)); @@ -1594,7 +1602,7 @@ static void check_interrupts_property(struct check *c, if (!irq_prop) return; - if (irq_prop->val.len % sizeof(cell_t)) + if (!is_multiple_of(irq_prop->val.len, sizeof(cell_t))) FAIL_PROP(c, dti, node, irq_prop, "size (%d) is invalid, expected multiple of %zu", irq_prop->val.len, sizeof(cell_t)); @@ -1643,7 +1651,7 @@ static void check_interrupts_property(struct check *c, } irq_cells = propval_cell(prop); - if (irq_prop->val.len % (irq_cells * sizeof(cell_t))) { + if (!is_multiple_of(irq_prop->val.len, irq_cells * sizeof(cell_t))) { FAIL_PROP(c, dti, node, prop, "size is (%d), expected multiple of %d", irq_prop->val.len, (int)(irq_cells * sizeof(cell_t))); |