In perl.git, the branch blead has been updated <https://perl5.git.perl.org/perl.git/commitdiff/1d48e83dd8863e78e8422ed502d9b2f3199193f5?hp=1d84a25665013f389ffc6fad7dd133f1c6287a08>
- Log ----------------------------------------------------------------- commit 1d48e83dd8863e78e8422ed502d9b2f3199193f5 Author: David Mitchell <[email protected]> Date: Wed Jun 19 13:03:22 2019 +0100 avoid use-after free in /(?{...})/ RT #134208 In something like eval { sub { " " }->() =~ /(?{ die })/ } When the match string gets aliased to $_, the SAVE_DEFSV is done after the SAVEDESTRUCTOR_X(S_cleanup_regmatch_info_aux). So if croaking, the SV gets SvREFCNT_dec()ed by the SAVE_DEFSV, then S_cleanup_regmatch_info_aux() manipulates the SV's magic. This doesn't cause a problem unless the match string is temporary, in which case the only other reference keeping it alive will be removed by the FREETMPs during the croak. The fix is to make sure an extra ref to the sv is held. ----------------------------------------------------------------------- Summary of changes: regexec.c | 4 ++++ regexp.h | 1 + t/re/pat_re_eval.t | 16 +++++++++++++++- 3 files changed, 20 insertions(+), 1 deletion(-) diff --git a/regexec.c b/regexec.c index e4ec07e89e..c390bff72e 100644 --- a/regexec.c +++ b/regexec.c @@ -10233,6 +10233,7 @@ S_setup_eval_state(pTHX_ regmatch_info *const reginfo) regmatch_info_aux_eval *eval_state = reginfo->info_aux_eval; eval_state->rex = rex; + eval_state->sv = reginfo->sv; if (reginfo->sv) { /* Make $_ available to executed code. */ @@ -10240,6 +10241,8 @@ S_setup_eval_state(pTHX_ regmatch_info *const reginfo) SAVE_DEFSV; DEFSV_set(reginfo->sv); } + /* will be dec'd by S_cleanup_regmatch_info_aux */ + SvREFCNT_inc_NN(reginfo->sv); if (!(mg = mg_find_mglob(reginfo->sv))) { /* prepare for quick setting of pos */ @@ -10331,6 +10334,7 @@ S_cleanup_regmatch_info_aux(pTHX_ void *arg) } PL_curpm = eval_state->curpm; + SvREFCNT_dec(eval_state->sv); } PL_regmatch_state = aux->old_regmatch_state; diff --git a/regexp.h b/regexp.h index 0f35205e1a..ccbc64a009 100644 --- a/regexp.h +++ b/regexp.h @@ -658,6 +658,7 @@ typedef struct { STRLEN sublen; /* saved sublen field from rex */ STRLEN suboffset; /* saved suboffset field from rex */ STRLEN subcoffset; /* saved subcoffset field from rex */ + SV *sv; /* $_ during (?{}) */ MAGIC *pos_magic; /* pos() magic attached to $_ */ SSize_t pos; /* the original value of pos() in pos_magic */ U8 pos_flags; /* flags to be restored; currently only MGf_BYTES*/ diff --git a/t/re/pat_re_eval.t b/t/re/pat_re_eval.t index 8325451377..696b6a3fb5 100644 --- a/t/re/pat_re_eval.t +++ b/t/re/pat_re_eval.t @@ -23,7 +23,7 @@ BEGIN { our @global; -plan tests => 504; # Update this when adding/deleting tests. +plan tests => 506; # Update this when adding/deleting tests. run_tests() unless caller; @@ -1317,6 +1317,20 @@ sub run_tests { ok "ABC" =~ /^ $runtime_re (?(?{ 0; })xy|BC) $/x, 'RT #133687 yes|no'; } + # RT #134208 + # when the string being matched was an SvTEMP and the re_eval died, + # the SV's magic was being restored after the SV was freed. + # Give ASan something to play with. + + { + my $a; + no warnings 'uninitialized'; + eval { "$a $1" =~ /(?{ die })/ }; + pass("SvTEMP 1"); + eval { sub { " " }->() =~ /(?{ die })/ }; + pass("SvTEMP 2"); + } + } # End of sub run_tests 1; -- Perl5 Master Repository
