Issue 35191: socket.setblocking(x) treats multiples of 2**32 as False

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/79372

classification

Title:	socket.setblocking(x) treats multiples of 2**32 as False
Type:	behavior	Stage:	patch review
Components:	Extension Modules	Versions:	Python 3.8, Python 3.7, Python 3.6, Python 2.7

process

Status:	open	Resolution:
Dependencies:		Superseder:
Assigned To:		Nosy List:	izbyshev, serhiy.storchaka, vstinner
Priority:	normal	Keywords:	patch

Created on 2018-11-08 15:43 by izbyshev, last changed 2022-04-11 14:59 by admin.

Pull Requests
URL	Status	Linked	Edit
PR 10415	open	izbyshev, 2018-11-08 15:46

Messages (1)
msg329478 - (view)	Author: Alexey Izbyshev (izbyshev) *	Date: 2018-11-08 15:43
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 (https://github.com/python/cpython/blob/fd512d76456b65c529a5bc58d8cfe73e4a10de7a/Modules/socketmodule.c#L2688). 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.

msg329478 - (view)

Author: Alexey Izbyshev (izbyshev) * (Python triager)

Date: 2018-11-08 15:43

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 (https://github.com/python/cpython/blob/fd512d76456b65c529a5bc58d8cfe73e4a10de7a/Modules/socketmodule.c#L2688). 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.

History
Date	User	Action	Args
2022-04-11 14:59:07	admin	set	github: 79372
2018-11-08 15:46:37	izbyshev	set	keywords: + patch stage: patch review pull_requests: + pull_request9695
2018-11-08 15:43:43	izbyshev	create