Hi Harald, It looks 'obvious' to me too and is certainly OK for master.
Thanks Paul On Thu, 18 Feb 2021 at 21:30, Harald Anlauf via Fortran <fort...@gcc.gnu.org> wrote: > Dear all, > > the PR reports an issue detected with an ASAN instrumented compiler, > which can also be verified with valgrind. It appears that the state > of gfc_new_block could be such that it should not be dereferenced. > Reversing the order of condition evaluation helped. > > I failed to find out why this should happen, but then other places > in the code put dereferences of gfc_new_block behind other checks. > Simple things like initializing gfc_new_block with NULL in decl.c > did not help. > > Regtested on x86_64-pc-linux-gnu. No testcase added since the issue > can be found only with an instrumented compiler or valgrind. > > I consider the patch to be obvious and trivial, but post it here > in case somebody wants to dig deeper. > > OK for master? > > Thanks, > Harald > > > PR fortran/99147 - Sanitizer detects heap-use-after-free in gfc_add_flavor > > Reverse order of conditions to avoid invalid read. > > gcc/fortran/ChangeLog: > > * symbol.c (gfc_add_flavor): Reverse order of conditions. > > -- "If you can't explain it simply, you don't understand it well enough" - Albert Einstein