From: Alexei Starovoitov <ast@kernel.org>
Date: Thu, 19 Nov 2020 18:45:55 +0000 (-0800)
Subject: Merge branch 'Fix bpf_probe_read_user_str() overcopying'
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=14d6d86c210aea1a83c19a8f6391ecabcbefed94;p=linux.git

Merge branch 'Fix bpf_probe_read_user_str() overcopying'

Daniel Xu says:

====================

6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user,
kernel}_str helpers") introduced a subtle bug where
bpf_probe_read_user_str() would potentially copy a few extra bytes after
the NUL terminator.

This issue is particularly nefarious when strings are used as map keys,
as seemingly identical strings can occupy multiple entries in a map.

This patchset fixes the issue and introduces a selftest to prevent
future regressions.

v6 -> v7:
* Add comments

v5 -> v6:
* zero-pad up to sizeof(unsigned long) after NUL

v4 -> v5:
* don't read potentially uninitialized memory

v3 -> v4:
* directly pass userspace pointer to prog
* test more strings of different length

v2 -> v3:
* set pid filter before attaching prog in selftest
* use long instead of int as bpf_probe_read_user_str() retval
* style changes

v1 -> v2:
* add Fixes: tag
* add selftest
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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14d6d86c210aea1a83c19a8f6391ecabcbefed94