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socket.setblocking(x) treats multiples of 2**32 as False #79372

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izbyshev mannequin opened this issue Nov 8, 2018 · 1 comment
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socket.setblocking(x) treats multiples of 2**32 as False #79372

izbyshev mannequin opened this issue Nov 8, 2018 · 1 comment
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3.7 (EOL) end of life 3.8 only security fixes extension-modules C modules in the Modules dir type-bug An unexpected behavior, bug, or error

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izbyshev mannequin commented Nov 8, 2018

BPO 35191
Nosy @vstinner, @serhiy-storchaka, @izbyshev
PRs
  • [3.11] bpo-35191: Fix unexpected integer truncation in socket.setblocking() #10415
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    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
closed_at = None
created_at = <Date 2018-11-08.15:43:43.083>
labels = ['extension-modules', '3.8', 'type-bug', '3.7']
title = 'socket.setblocking(x) treats multiples of 2**32 as False'
updated_at = <Date 2018-11-08.15:46:37.663>
user = 'https://github.com/izbyshev'

    bugs.python.org fields:

    activity = <Date 2018-11-08.15:46:37.663>
actor = 'izbyshev'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Extension Modules']
creation = <Date 2018-11-08.15:43:43.083>
creator = 'izbyshev'
dependencies = []
files = []
hgrepos = []
issue_num = 35191
keywords = ['patch']
message_count = 1.0
messages = ['329478']
nosy_count = 3.0
nosy_names = ['vstinner', 'serhiy.storchaka', 'izbyshev']
pr_nums = ['10415']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue35191'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7', 'Python 3.8']
    @izbyshev
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    izbyshev mannequin commented Nov 8, 2018

    UBSAN with -fsanitize=implicit-integer-truncation reported a suspicious case:

    testSetBlocking_overflow (test.test_socket.NonBlockingTCPTests) ... /scratch2/izbyshev/cpython/Modules/socketmodule.c:2688:33: runtime error: implicit conversion from type 'long' of value 4294967296 (64-bit, signed) to type 'int' changed the value to 0 (32-bit, signed)

    It turned out that sock_setblocking() converts its (logically boolean) argument to long, but then passes it to internal_setblocking() which accepts int (

    cpython/Modules/socketmodule.c

    Line 2688 in fd512d7

    if (internal_setblocking(s, block) == -1) {
    ). This results in unexpected truncation on platforms with 64-bit long.

    testSetBlocking_overflow() which is supposed to check this doesn't work because it only checks socket timeout which is updated correctly. However, the actual state of socket descriptor is changed to the opposite value (non-blocking) in this case.

    @izbyshev izbyshev mannequin added 3.7 (EOL) end of life 3.8 only security fixes extension-modules C modules in the Modules dir type-bug An unexpected behavior, bug, or error labels Nov 8, 2018
    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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