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Bug #9259 crash when accessing shared memory + more info on bug #8985
Submitted: 2001-02-14 08:47 UTC Modified: 2002-02-15 00:00 UTC
Votes:1
Avg. Score:5.0 ± 0.0
Reproduced:0 of 0 (0.0%)
From: fuf at mobil dot cz Assigned:
Status: No Feedback Package: Semaphore related
PHP Version: 4.0.4pl1 OS: linux-2.2.18
Private report: No CVE-ID: None
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 [2001-02-14 08:47 UTC] fuf at mobil dot cz
hello,

  when accessing a shared memory region that i don't have access to (because of the permissions), php segfaults.
  so if i have a shared memory region created by another user with key 0x123 and permissions 0600 and call shm_attach(0x123), php crashes:
	<?
		$shmid = shm_attach(0x123);
		shm_detach(0x123);
	?>

  also, i know some more info concerning the bug #8985: when one process is reading some variable from the shared memory and some other is writing _another_ variable to the same shared memory region, the data gets corrupted - possibly because of the reorganizing before each shm_put_var(). while this is understandable (shm_put_var() first removes the variable, reorganizes the region and writes the variable back), it renders this extension almost unusable in multitasking environments because a big global lock for the whole shared memory region is needed.
  i can supply more information if needed of course.

	thanks,
		Michal Vitecek

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 [2002-01-14 02:25 UTC] lobbin@php.net
Does this happen on 4.1.1?
 [2002-01-14 02:31 UTC] lobbin@php.net
-> feedback
 [2002-02-15 00:00 UTC] php-bugs at lists dot php dot net
No feedback was provided for this bug for over a month, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".
 
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