[sdcc-devel] [ sdcc-Patches-1708427 ] Avoid accessing a NULL pointer in src/pic/pcode.c

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Patches item #1708427, was opened at 2007-04-26 23:10
Message generated for change (Comment added) made by tecodev
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Category: None
Group: None
>Status: Closed
>Resolution: Accepted
Priority: 5
Private: No
Submitted By: Kevin Buettner (kbuettner)
Assigned to: Nobody/Anonymous (nobody)
Summary: Avoid accessing a NULL pointer in src/pic/pcode.c

Initial Comment:
This patch fixes a SIGSEGV that I encountered while developing some code for a pic12f683.  Here's what gdb tells me:

Breakpoint 1, pBlockRemoveUnusedLabels (pb=0x99a6610) at pcode.c:4890
4890            if(!pb)
(gdb) p pb
$3 = (pBlock *) 0x99a6610
(gdb) n
4893            for(pc = pb->pcHead; (pc=findNextInstruction(pc->next)) != NULL;
 ) {
(gdb) p pb
$4 = (pBlock *) 0x99a6610
(gdb) p *pb
$5 = {cmemmap = 0x0, dbName = 87 'W', pcHead = 0x0, pcTail = 0x0, next = 0x0, 
  prev = 0x0, function_entries = 0x0, function_exits = 0x0, 
  function_calls = 0x0, tregisters = 0x0, FlowTree = 0x0, visited = 0, seq = 0}
(gdb) bt 
#0  pBlockRemoveUnusedLabels (pb=0x99a6610) at pcode.c:4893
#1  0x08140849 in peepRules2pCode (rules=0x999cfe8) at pcodepeep.c:1368
#2  0x080a708b in initPeepHole () at SDCCpeeph.c:2334
#3  0x080544c5 in main (argc=4, argv=<value optimized out>, envp=0xbfd55c08)
    at SDCCmain.c:2462

When pb->pcHead is 0 (as it is in this case), setting pc to this value will cause a SIGSEGV when accessing pc->next.

Kevin

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>Comment By: Raphael Neider (tecodev)
Date: 2007-04-27 08:35

Message:
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user_id=1115835
Originator: NO

Applied with some additions in SDCC r4772.

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