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Date: Mon, 18 Dec 2017 16:27:02 +0100
From: Marcus Meissner <meissner@...e.de>
To: OSS Security List <oss-security@...ts.openwall.com>
Subject: overly broad IPC details sharing on Linux Kernel?

Hi,

spotted by one of our customers...

shmctl(id, IPC_STAT, &buf)

returns the STAT information _only_ if the calling user has read-access to the "id" shared memory segment.

However, the proc entries in /proc/sysvipc/shm  return the entries for all users shared memory segments,
even if there is no read permission.

There is a bit of information leakage in the access times, but I currently do not see
any direct exploitability.

Regardless ... should the /proc/sysvipc/* files be restricted?

Ciao, Marcus

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