diff options
| author | cinap_lenrek <cinap_lenrek@felloff.net> | 2018-07-27 09:31:28 +0200 |
|---|---|---|
| committer | cinap_lenrek <cinap_lenrek@felloff.net> | 2018-07-27 09:31:28 +0200 |
| commit | da5c0bada7be9dd82ca1f63e621670143597d3bb (patch) | |
| tree | 6ac3f33deb497df5139dea50921a186e7e8d96ed /sys/src/cmd/dc.c | |
| parent | 6cd83e5d246753f2b8691dded4697f858a9cd513 (diff) | |
dc: fix off by one in stack overflow check (thanks BurnZeZ)
BurnZeZ → Found a bug in dc(1)
BurnZeZ → Everything breaks when you fill the stack
BurnZeZ → You have stkptr which crap expects to point to an available member in Blk *stack[STKSZ];
BurnZeZ → stkend = &stack[STKSZ];
BurnZeZ → stkptr is allowed to equal stkend
BurnZeZ → So crap that expects stkptr to be pointing to an available Blk ends up dereferencing past the end of the array
BurnZeZ → term% echo `{seq 1 100} f | dc
BurnZeZ → dc 628283: suicide: sys: trap: fault read addr=0xffffe0000040a618 pc=0x204b1c
Diffstat (limited to 'sys/src/cmd/dc.c')
| -rw-r--r-- | sys/src/cmd/dc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sys/src/cmd/dc.c b/sys/src/cmd/dc.c index c121b13d8..abc7060fd 100644 --- a/sys/src/cmd/dc.c +++ b/sys/src/cmd/dc.c @@ -1218,7 +1218,7 @@ init(int argc, char *argv[]) strptr = salloc(0); divxyz = salloc(0); stkbeg = stkptr = &stack[0]; - stkend = &stack[STKSZ]; + stkend = &stack[STKSZ-1]; stkerr = 0; readptr = &readstk[0]; k=0; |