[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

STINNER Victor  added the comment:

Thanks for the report Charalampos. I fixed dtoa.c in 2.7, 3.7 and master 
branches.

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resolution:  -> fixed
stage: patch review -> resolved
status: open -> closed

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[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

STINNER Victor  added the comment:


New changeset b14057877fd897eaee7bc6626682fc6092b6bbd2 by Victor Stinner in 
branch '2.7':
bpo-36262: Fix _Py_dg_strtod() memory leak (goto undfl) (GH-12276) (GH-12332)
https://github.com/python/cpython/commit/b14057877fd897eaee7bc6626682fc6092b6bbd2


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[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

STINNER Victor  added the comment:


New changeset 9818360ed94b39c4605951077b73ae798cddbfb9 by Victor Stinner in 
branch '3.7':
bpo-36262: Fix _Py_dg_strtod() memory leak (goto undfl) (GH-12276) (GH-12331)
https://github.com/python/cpython/commit/9818360ed94b39c4605951077b73ae798cddbfb9


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[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

Change by STINNER Victor :


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pull_requests: +12303

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[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

Change by STINNER Victor :


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pull_requests: +12302

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[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

STINNER Victor  added the comment:


New changeset 9776b0636ae39668d3ce1c006d4be01dad01bf9f by Victor Stinner in 
branch 'master':
bpo-36262: Fix _Py_dg_strtod() memory leak (goto undfl) (GH-12276)
https://github.com/python/cpython/commit/9776b0636ae39668d3ce1c006d4be01dad01bf9f


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[issue36262] Coverity scan: Python/dtoa.c resource leak

[Mark Dickinson]

Mark Dickinson  added the comment:

> ... in practice, it seems like Python became the "upstream".

Yes; unfortunately, we changed things enough that updating from upstream became 
impractical. At some point we should take a look at changes made to the 
upstream dtoa.c since our adoption of it, and figure out whether any of those 
changes need to be applied to our copy. That's not going to be an easy task. It 
would be easier if there were upstream testcases (and regression tests in 
particular), but as far as I'm aware there aren't any.

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[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

Change by STINNER Victor :


--
keywords: +patch
pull_requests: +12256
stage:  -> patch review

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[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

STINNER Victor  added the comment:

Julia copied the same file. See:

* https://bugs.llvm.org//show_bug.cgi?id=31928
* https://bugs.freebsd.org/216770
* https://bugs.python.org/issue30104: "It was decided to not touch dtoa.c to 
not diverge from upstream."

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[issue36262] Coverity scan: Python/dtoa.c resource leak

[STINNER Victor]

STINNER Victor  added the comment:

* bpo-9009 discussed maintenance of Python/dtoa.c
* Python/dtoa.c asks to frequently update it from "upstream" 
http://www.netlib.org/fp/dtoa.c
* The upstream is also mentioned in the license: 
https://docs.python.org/dev/license.html#strtod-and-dtoa

... in practice, it seems like Python became the "upstream". I see lot of 
changes, but I'm not sure that version maintained by David M. Gay on 
http://www.netlib.org/fp/dtoa.c has been updated since Mark Dickinson copied it 
to Python/dtoa.c:

commit b08a53a99def3fa949643974f713b5b189e21bc7
Author: Mark Dickinson 
Date:   Thu Apr 16 19:52:09 2009 +

Issue #1580: use short float repr where possible.
 - incorporate and adapt David Gay's dtoa and strtod
   into the Python core
 - on platforms where we can use Gay's code (almost
   all!), repr(float) is based on the shortest
   sequence of decimal digits that rounds correctly.
 - add sys.float_repr_style attribute to indicate
   whether we're using Gay's code or not
 - add autoconf magic to detect and enable SSE2
   instructions on x86/gcc
 - slight change to repr and str:  repr switches
   to exponential notation at 1e16 instead of
   1e17, str switches at 1e11 instead of 1e12

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[issue36262] Coverity scan: Python/dtoa.c resource leak

[Charalampos Stratakis]

Change by Charalampos Stratakis :


--
nosy: +mark.dickinson, vstinner

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[issue36262] Coverity scan: Python/dtoa.c resource leak

[Charalampos Stratakis]

New submission from Charalampos Stratakis :

Coverity report on dtoa.c. It was run on python2 but the same code resides on 
python3.

Error: RESOURCE_LEAK (CWE-772): [#def89]
Python-2.7.15/Python/dtoa.c:1846: alloc_fn: Storage is returned from allocation 
function "s2b".
Python-2.7.15/Python/dtoa.c:526:9: alloc_fn: Storage is returned from 
allocation function "multadd".
Python-2.7.15/Python/dtoa.c:479:13: alloc_fn: Storage is returned from 
allocation function "Balloc".
Python-2.7.15/Python/dtoa.c:371:13: alloc_fn: Storage is returned from 
allocation function "PyMem_Malloc".
Python-2.7.15/Objects/object.c:2348:5: alloc_fn: Storage is returned from 
allocation function "malloc".
Python-2.7.15/Objects/object.c:2348:5: return_alloc_fn: Directly returning 
storage allocated by "malloc".
Python-2.7.15/Python/dtoa.c:371:13: var_assign: Assigning: "rv" = 
"PyMem_Malloc(len * 8UL)".
Python-2.7.15/Python/dtoa.c:379:5: return_alloc: Returning allocated memory 
"rv".
Python-2.7.15/Python/dtoa.c:479:13: var_assign: Assigning: "b1" = "Balloc(b->k 
+ 1)".
Python-2.7.15/Python/dtoa.c:486:13: var_assign: Assigning: "b" = "b1".
Python-2.7.15/Python/dtoa.c:491:5: return_alloc: Returning allocated memory "b".
Python-2.7.15/Python/dtoa.c:526:9: var_assign: Assigning: "b" = "multadd(b, 10, 
*s++ - 48)".
Python-2.7.15/Python/dtoa.c:530:5: return_alloc: Returning allocated memory "b".
Python-2.7.15/Python/dtoa.c:1846: var_assign: Assigning: "bd0" = storage 
returned from "s2b(s0, nd0, nd, y)".
Python-2.7.15/Python/dtoa.c:2249: leaked_storage: Variable "bd0" going out of 
scope leaks the storage it points to.
 2247|   
 2248| undfl:
 2249|-> return sign ? -0.0 : 0.0;
 2250|   
 2251| ovfl:

Error: RESOURCE_LEAK (CWE-772): [#def90]
Python-2.7.15/Python/dtoa.c:2006: alloc_fn: Storage is returned from allocation 
function "diff".
Python-2.7.15/Python/dtoa.c:952:5: alloc_fn: Storage is returned from 
allocation function "Balloc".
Python-2.7.15/Python/dtoa.c:371:13: alloc_fn: Storage is returned from 
allocation function "PyMem_Malloc".
Python-2.7.15/Objects/object.c:2348:5: alloc_fn: Storage is returned from 
allocation function "malloc".
Python-2.7.15/Objects/object.c:2348:5: return_alloc_fn: Directly returning 
storage allocated by "malloc".
Python-2.7.15/Python/dtoa.c:371:13: var_assign: Assigning: "rv" = 
"PyMem_Malloc(len * 8UL)".
Python-2.7.15/Python/dtoa.c:379:5: return_alloc: Returning allocated memory 
"rv".
Python-2.7.15/Python/dtoa.c:952:5: var_assign: Assigning: "c" = "Balloc(a->k)".
Python-2.7.15/Python/dtoa.c:962:5: var_assign: Assigning: "xc" = "c".
Python-2.7.15/Python/dtoa.c:996:5: return_alloc: Returning allocated memory "c".
Python-2.7.15/Python/dtoa.c:2006: var_assign: Assigning: "delta" = storage 
returned from "diff(bb, bd)".
Python-2.7.15/Python/dtoa.c:2016: noescape: Resource "delta" is not freed or 
pointed-to in "cmp".
Python-2.7.15/Python/dtoa.c:890:13: noescape: "cmp(Bigint *, Bigint *)" does 
not free or save its parameter "a".
Python-2.7.15/Python/dtoa.c:2129: noescape: Resource "delta" is not freed or 
pointed-to in "ratio".
Python-2.7.15/Python/dtoa.c:1179:15: noescape: "ratio(Bigint *, Bigint *)" does 
not free or save its parameter "a".
Python-2.7.15/Python/dtoa.c:2249: leaked_storage: Variable "delta" going out of 
scope leaks the storage it points to.
 2247|   
 2248| undfl:
 2249|-> return sign ? -0.0 : 0.0;
 2250|   
 2251| ovfl:

--
components: Interpreter Core
messages: 337668
nosy: cstratak
priority: normal
severity: normal
status: open
title: Coverity scan: Python/dtoa.c resource leak
versions: Python 2.7, Python 3.7, Python 3.8

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