Date: Fri, 23 Dec 2022 16:49:43 +0000 From: Simon McVittie <smcv@...ian.org> To: oss-security@...ts.openwall.com Subject: Re: [Linux] /proc/pid/stat parsing bugs On Thu, 22 Dec 2022 at 10:04:48 -0500, Shawn Webb wrote: > We knew way back then the dangers of VFS-based wizardry. Did we lose > that knowledge somehow? To me this seems like a parsing problem, not a VFS problem. Some pseudo-files in Linux /proc are one file per item (/proc/self/oom_adj, /proc/self/sessionid, most of /proc/sys) and those are fine: the structure is implicit in the filesystem layout, and the file contents are trivial to "parse". Others have a simple and well-defined format (like /proc/self/environ and /proc/self/cmdline, which are sequences of \0-terminated bytestrings), and those also seem fine. It's the pseudo-files that contain more than one item, particularly those with a semi-consistent format that aims for human-readability, that can easily get into escaping and parsing issues. If those pseudo-files made *more* use of the VFS (one new file in /proc/self for each field in the current /proc/self/stat?) then they would suffer from different issues instead, like inability to read all fields atomically and maybe performance issues for heavy users, but parsing would become a non-issue. smcv  or when they're not fine, the issues are around things like how to separate an AppArmor enforcement mode from the label, which again is a matter of parsing a human-readable format with structure
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.