PHP 4.0 Bug #9259: crash when accessing shared memory + more info on bug #8985

From: Date: Wed, 14 Feb 2001 13:47:02 +0000
Subject: PHP 4.0 Bug #9259: crash when accessing shared memory + more info on bug #8985
Groups: php.dev 
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From: fuf@mobil.cz Operating system: linux-2.2.18 PHP version: 4.0.4pl1 PHP Bug Type: Reproduceable crash Bug description: crash when accessing shared memory + more info on bug #8985 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 -- Edit Bug report at: http://bugs.php.net/?id=9259&edit=1

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