Hi Simon ! Thanks for your feedback.
On Mon, 2011-04-25 at 21:20 +0200, Simon Josefsson wrote: > Guido Trentalancia <[email protected]> writes: > > > Hello Simon ! > > Hi! I re-added help-libidn on the cc list, please keep it so that > others can learn from our discussion. > > > Here is the output with -g added: > .. > > ==31295== Invalid read of size 4 > > ==31295== at 0x402E46: idna_to_ascii_4z (idna.c:516) > ... > > ==31295== Address 0x51ca8d8 is 8 bytes inside a block of size 10 > > alloc'd > > ==31295== at 0x4C282CD: malloc (vg_replace_malloc.c:236) > > ==31295== by 0x402F90: idna_to_ascii_4z (idna.c:528) > ... > > Using only -g in the CFLAGS and dropping all the rest (-O3 and > > processor-specific optimisations) produces no errors. > > > > The problem is triggered by -O3, -O2 but not -O1. > > That offending line contains a strlen. I think this is just a matter of > the compiler chosing a (too) optimized 'strlen' implementation that > reads in chunks of 4 bytes even when the buffer is shorter. In this > case, it reads 4 + 4 + 4 bytes but the buffer is only 10 bytes Since we are not testing the compiler here, could we not avoid the optimisation even when the user has explictly requested it ? Using strnlen for example would lead to the same optimisation ? > It could be a compiler bug, but I suspect it is intentional to read even > beyond the end of a buffer because it will be faster. Thus, unless it > is a compiler bug, you need to compile with the default compiler flags > or specify --disable-valgrind-tests when building libidn. At least you could add a note...? > I hope this answers everything. > > /Simon Regards, Guido _______________________________________________ Help-libidn mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-libidn
