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Fix some UB cases. Closes #546 

There are two cases of UB that are fixed in this commit.

1. In ethercatmain.c, there are two left shifts of 31:

    (1 << 31)

Because 1 is a signed int by default, the result cannot be represented
in an int. The fix is to explicitly make the 1 unsigned.

2. In ethercatconfig.c, for slaves that have no inputs, the code would
   apply an offset to a NULL pointer. The fix is to test that the slave
   has inputs available before applying the offset.

Both cases were found by clang with the help of UBSan.
This commit is contained in:
Michael Egli 2021-08-31 06:47:48 +02:00
parent be1a2df6b2
commit ff448e3485
2 changed files with 6 additions and 3 deletions
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5
soem/ethercatconfig.c
View File

@ -1474,7 +1474,10 @@ int ecx_config_overlap_map_group(ecx_contextt *context, void *pIOmap, uint8 grou
{ {
if (!group || (group == context->slavelist[slave].group)) if (!group || (group == context->slavelist[slave].group))
{ {
context->slavelist[slave].inputs += context->grouplist[group].Obytes; if(context->slavelist[slave].Ibits > 0)
{
context->slavelist[slave].inputs += context->grouplist[group].Obytes;
}
} }
} }

4
soem/ethercatmain.c
View File

@ -349,7 +349,7 @@ uint8 ecx_siigetbyte(ecx_contextt *context, uint16 slave, uint16 address)
{ {
mapw = address >> 5; mapw = address >> 5;
mapb = (uint16)(address - (mapw << 5)); mapb = (uint16)(address - (mapw << 5));
if (context->esimap[mapw] & (uint32)(1 << mapb)) if (context->esimap[mapw] & (1U << mapb))
{ {
/* byte is already in buffer */ /* byte is already in buffer */
retval = context->esibuf[address]; retval = context->esibuf[address];
@ -380,7 +380,7 @@ uint8 ecx_siigetbyte(ecx_contextt *context, uint16 slave, uint16 address)
for(lp = 0 ; lp < cnt ; lp++) for(lp = 0 ; lp < cnt ; lp++)
{ {
/* set bitmap for each byte that is read */ /* set bitmap for each byte that is read */
context->esimap[mapw] |= (1 << mapb); context->esimap[mapw] |= (1U << mapb);
mapb++; mapb++;
if (mapb > 31) if (mapb > 31)
{ {