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serhiy-storchakaserhiy-storchaka
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Issue #18684: Fixed reading out of the buffer in the re module.
2 parents 7afe40e + 02eae6b commit 5bccb29

3 files changed

Lines changed: 43 additions & 14 deletions

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‎Misc/NEWS‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -33,6 +33,8 @@ Core and Builtins
3333
Library
3434
-------
3535

36+
- Issue #18684: Fixed reading out of the buffer in the re module.
37+
3638
- Issue #24259: tarfile now raises a ReadError if an archive is truncated
3739
inside a data segment.
3840

‎Modules/_sre.c‎

Lines changed: 21 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -991,7 +991,7 @@ _sre_SRE_Pattern_split_impl(PatternObject *self, PyObject *string,
991991
}
992992

993993
if (state.start == state.ptr) {
994-
if (last == state.end)
994+
if (last == state.end || state.ptr == state.end)
995995
break;
996996
/* skip one character */
997997
state.start = (void*) ((char*) state.ptr + state.charsize);
@@ -1188,6 +1188,8 @@ pattern_subx(PatternObject* self, PyObject* ptemplate, PyObject* string,
11881188

11891189
next:
11901190
/* move on */
1191+
if (state.ptr == state.end)
1192+
break;
11911193
if (state.ptr == state.start)
11921194
state.start = (void*) ((char*) state.ptr + state.charsize);
11931195
else
@@ -2561,6 +2563,9 @@ _sre_SRE_Scanner_match_impl(ScannerObject *self)
25612563
PyObject* match;
25622564
Py_ssize_t status;
25632565

2566+
if (state->start == NULL)
2567+
Py_RETURN_NONE;
2568+
25642569
state_reset(state);
25652570

25662571
state->ptr = state->start;
@@ -2572,10 +2577,14 @@ _sre_SRE_Scanner_match_impl(ScannerObject *self)
25722577
match = pattern_new_match((PatternObject*) self->pattern,
25732578
state, status);
25742579

2575-
if (status == 0 || state->ptr == state->start)
2580+
if (status == 0)
2581+
state->start = NULL;
2582+
else if (state->ptr != state->start)
2583+
state->start = state->ptr;
2584+
else if (state->ptr != state->end)
25762585
state->start = (void*) ((char*) state->ptr + state->charsize);
25772586
else
2578-
state->start = state->ptr;
2587+
state->start = NULL;
25792588

25802589
return match;
25812590
}
@@ -2594,6 +2603,9 @@ _sre_SRE_Scanner_search_impl(ScannerObject *self)
25942603
PyObject* match;
25952604
Py_ssize_t status;
25962605

2606+
if (state->start == NULL)
2607+
Py_RETURN_NONE;
2608+
25972609
state_reset(state);
25982610

25992611
state->ptr = state->start;
@@ -2605,10 +2617,14 @@ _sre_SRE_Scanner_search_impl(ScannerObject *self)
26052617
match = pattern_new_match((PatternObject*) self->pattern,
26062618
state, status);
26072619

2608-
if (status == 0 || state->ptr == state->start)
2620+
if (status == 0)
2621+
state->start = NULL;
2622+
else if (state->ptr != state->start)
2623+
state->start = state->ptr;
2624+
else if (state->ptr != state->end)
26092625
state->start = (void*) ((char*) state->ptr + state->charsize);
26102626
else
2611-
state->start = state->ptr;
2627+
state->start = NULL;
26122628

26132629
return match;
26142630
}

‎Modules/sre_lib.h‎

Lines changed: 20 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -30,7 +30,7 @@ SRE(at)(SRE_STATE* state, SRE_CHAR* ptr, SRE_CODE at)
3030
SRE_IS_LINEBREAK((int) ptr[-1]));
3131

3232
case SRE_AT_END:
33-
return (((void*) (ptr+1) == state->end &&
33+
return (((SRE_CHAR *)state->end - ptr == 1 &&
3434
SRE_IS_LINEBREAK((int) ptr[0])) ||
3535
((void*) ptr == state->end));
3636

@@ -1109,9 +1109,9 @@ SRE(match)(SRE_STATE* state, SRE_CODE* pattern, int match_all)
11091109
/* <ASSERT> <skip> <back> <pattern> */
11101110
TRACE(("|%p|%p|ASSERT %d\n", ctx->pattern,
11111111
ctx->ptr, ctx->pattern[1]));
1112-
state->ptr = ctx->ptr - ctx->pattern[1];
1113-
if (state->ptr < state->beginning)
1112+
if (ctx->ptr - (SRE_CHAR *)state->beginning < (Py_ssize_t)ctx->pattern[1])
11141113
RETURN_FAILURE;
1114+
state->ptr = ctx->ptr - ctx->pattern[1];
11151115
DO_JUMP0(JUMP_ASSERT, jump_assert, ctx->pattern+2);
11161116
RETURN_ON_FAILURE(ret);
11171117
ctx->pattern += ctx->pattern[0];
@@ -1122,8 +1122,8 @@ SRE(match)(SRE_STATE* state, SRE_CODE* pattern, int match_all)
11221122
/* <ASSERT_NOT> <skip> <back> <pattern> */
11231123
TRACE(("|%p|%p|ASSERT_NOT %d\n", ctx->pattern,
11241124
ctx->ptr, ctx->pattern[1]));
1125-
state->ptr = ctx->ptr - ctx->pattern[1];
1126-
if (state->ptr >= state->beginning) {
1125+
if (ctx->ptr - (SRE_CHAR *)state->beginning >= (Py_ssize_t)ctx->pattern[1]) {
1126+
state->ptr = ctx->ptr - ctx->pattern[1];
11271127
DO_JUMP0(JUMP_ASSERT_NOT, jump_assert_not, ctx->pattern+2);
11281128
if (ret) {
11291129
RETURN_ON_ERROR(ret);
@@ -1215,12 +1215,20 @@ SRE(search)(SRE_STATE* state, SRE_CODE* pattern)
12151215
SRE_CODE* overlap = NULL;
12161216
int flags = 0;
12171217

1218+
if (ptr > end)
1219+
return 0;
1220+
12181221
if (pattern[0] == SRE_OP_INFO) {
12191222
/* optimization info block */
12201223
/* <INFO> <1=skip> <2=flags> <3=min> <4=max> <5=prefix info> */
12211224

12221225
flags = pattern[2];
12231226

1227+
if (pattern[3] && end - ptr < (Py_ssize_t)pattern[3]) {
1228+
TRACE(("reject (got %u chars, need %u)\n",
1229+
(unsigned int)(end - ptr), pattern[3]));
1230+
return 0;
1231+
}
12241232
if (pattern[3] > 1) {
12251233
/* adjust end point (but make sure we leave at least one
12261234
character in there, so literal search will work) */
@@ -1339,15 +1347,18 @@ SRE(search)(SRE_STATE* state, SRE_CODE* pattern)
13391347
break;
13401348
ptr++;
13411349
}
1342-
} else
1350+
} else {
13431351
/* general case */
1344-
while (ptr <= end) {
1352+
assert(ptr <= end);
1353+
while (1) {
13451354
TRACE(("|%p|%p|SEARCH\n", pattern, ptr));
1346-
state->start = state->ptr = ptr++;
1355+
state->start = state->ptr = ptr;
13471356
status = SRE(match)(state, pattern, 0);
1348-
if (status != 0)
1357+
if (status != 0 || ptr >= end)
13491358
break;
1359+
ptr++;
13501360
}
1361+
}
13511362

13521363
return status;
13531364
}

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