On Thu, Mar 12, 2015 at 02:21:12AM +0300, Alexey Brodkin wrote: > On execution of "inet/gethost_r-align" test I noticed failure due > to unaligned access (instaed of 4-byte aligned 1-byte aligned > address was attempted to be accessed). > > Further investigation confirmed this nice and helpful test failure. > Following commit removed usage of ALIGN_BUFFER_OFFSET on entry to > __read_etc_hosts_r(): > http://git.uclibc.org/uClibc/commit/?id=f65e66078b9f4d2d7f0fc336dee36e78fc467c0f > > So indeed if target architecture doesn't allow unaligned access > and provided tmp buffer is not word aligned (and we will deal with pointers > which means word-sized data units), then CPU will fail during execution. > > In case of ARC we'll see "Unaligned access" exception like this: > --->8--- > # potentially unexpected fatal signal 7. > Path: /root/uClibc/test/inet/gethost_r-align > CPU: 0 PID: 5514 Comm: gethost_r-align Not tainted 3.13.11 #2 > task: 8f42a580 ti: 8f40e000 task.ti: 8f40e000 > > [ECR ]: 0x00230400 => Misaligned r/w from 0x5fdab341 > [EFA ]: 0x5fdab341 > [BLINK ]: 0x20032a18 > [ERET ]: 0x20032a3c > @off 0x12a3c in [/lib/libuClibc-0.9.34-git.so] > VMA: 0x20020000 to 0x20062000 > [STAT32]: 0x00000086 : U E2 E1 > BTA: 0x20046014 SP: 0x5fdab260 FP: 0x00000000 > LPS: 0x20046064 LPE: 0x20046068 LPC: 0x00000000 > r00: 0x5fdab341 r01: 0x00000005 r02: 0x00000015 > r03: 0x00000000 r04: 0x5fdab358 r05: 0x00000000 > r06: 0x0a0a0a00 r07: 0x00000000 r08: 0x0000003f > r09: 0x20067050 r10: 0x00000000 r11: 0x00000014 > r12: 0x00000001 r13: 0x00000000 r14: 0x20060660 > r15: 0x20060661 r16: 0x00000006 r17: 0x5fdab371 > r18: 0x00000018 r19: 0x5fdab2b4 r20: 0x00020000 > r21: 0x00000000 r22: 0x00029068 r23: 0x5fdab371 > r24: 0x00010000 r25: 0x00000000 > --->8--- > > To fix this problem we'll re-introduce tmp buffer force alignment > before config parser invocation. > > Signed-off-by: Alexey Brodkin <[email protected]> > Cc: Vineet Gupta <[email protected]> > Cc: Waldemar Brodkorb <[email protected]> > --- > libc/inet/resolv.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c > index cfc1eee..7c678ce 100644 > --- a/libc/inet/resolv.c > +++ b/libc/inet/resolv.c > @@ -1614,7 +1614,7 @@ int __read_etc_hosts_r( > sizeof(struct in_addr) > #endif > ; > - int ret = HOST_NOT_FOUND; > + int i, ret = HOST_NOT_FOUND; > > *h_errnop = NETDB_INTERNAL; > if (buflen < aliaslen > @@ -1626,6 +1626,12 @@ int __read_etc_hosts_r( > *result = NULL; > return errno; > } > + > + /* make sure pointer is aligned */ > + i = ALIGN_BUFFER_OFFSET(buf); > + buf += i; > + buflen -= i;
Is this safe against the possibility of buflen<i? Otherwise you're introducing a serious overflow. Rich _______________________________________________ uClibc mailing list [email protected] http://lists.busybox.net/mailman/listinfo/uclibc
