Anastasia Klimchuk submitted this change.
ich_descriptors.c: Ensure unsigned types >=0 on to prevent underflow
Unsigned types show undefined behaviour if they are subtracted by a
value greater than their own (mostly it wraps to the max value). Using
this value for left shifting could be even more dangerous.
Change-Id: I5921cc571f3dca5188ca1973dba6ececbcbe2f39
Signed-off-by: Aarya Chaumal <aarya.chaumal@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/62764
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
---
M ich_descriptors.c
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/ich_descriptors.c b/ich_descriptors.c
index 7c03499..4d85e08 100644
--- a/ich_descriptors.c
+++ b/ich_descriptors.c
@@ -502,16 +502,17 @@
msg_pdbg2(" RegA RegB RegC RegD RegE RegF\n");
}
for (i = 0; i < nm; i++) {
+ const unsigned int ext_region_start = 12;
size_t j;
msg_pdbg2("%-4s", master_names[i]);
- for (j = 0; j < (size_t)min(num_regions, 12); j++)
+ for (j = 0; j < (size_t)min(num_regions, ext_region_start); j++)
msg_pdbg2(" %c%c ",
desc->master.mstr[i].read & (1 << j) ? 'r' : ' ',
desc->master.mstr[i].write & (1 << j) ? 'w' : ' ');
- for (; j < num_regions; j++)
+ for (j = ext_region_start; j < num_regions; j++)
msg_pdbg2(" %c%c ",
- desc->master.mstr[i].ext_read & (1 << (j - 12)) ? 'r' : ' ',
- desc->master.mstr[i].ext_write & (1 << (j - 12)) ? 'w' : ' ');
+ desc->master.mstr[i].ext_read & (1 << (j - ext_region_start)) ? 'r' : ' ',
+ desc->master.mstr[i].ext_write & (1 << (j - ext_region_start)) ? 'w' : ' ');
msg_pdbg2("\n");
}
} else if (cs == CHIPSET_C620_SERIES_LEWISBURG) {
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