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From: Daniel Xu <dxu@dxuuu.xyz>
To: bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	ast@kernel.org, daniel@iogearbox.net
Cc: Daniel Xu <dxu@dxuuu.xyz>, kernel-team@fb.com
Subject: [PATCH bpf v2 0/2] Fix bpf_probe_read_user_str() overcopying
Date: Wed,  4 Nov 2020 18:25:36 -0800	[thread overview]
Message-ID: <cover.1604542786.git.dxu@dxuuu.xyz> (raw)

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.

Daniel Xu (2):
  lib/strncpy_from_user.c: Don't overcopy bytes after NUL terminator
  selftest/bpf: Test bpf_probe_read_user_str() strips trailing bytes
    after NUL

 lib/strncpy_from_user.c                       |  9 ++-
 .../bpf/prog_tests/probe_read_user_str.c      | 60 +++++++++++++++++++
 .../bpf/progs/test_probe_read_user_str.c      | 34 +++++++++++
 3 files changed, 101 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_probe_read_user_str.c

-- 
2.28.0


             reply	other threads:[~2020-11-05  2:26 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-05  2:25 Daniel Xu [this message]
2020-11-05  2:25 ` [PATCH bpf v2 1/2] lib/strncpy_from_user.c: Don't overcopy bytes after NUL terminator Daniel Xu
2020-11-05  9:00   ` David Laight
2020-11-05 18:16   ` Song Liu
2020-11-05 18:18     ` Song Liu
2020-11-05 19:28     ` Daniel Xu
2020-11-15 10:41   ` [lib/strncpy_from_user.c] 2903f3d558: Kernel_panic-not_syncing:Attempted_to_kill_init!exitcode= kernel test robot
2020-11-05  2:25 ` [PATCH bpf v2 2/2] selftest/bpf: Test bpf_probe_read_user_str() strips trailing bytes after NUL Daniel Xu
2020-11-05 18:30   ` Song Liu
2020-11-05 19:27     ` Daniel Xu
2020-11-05 21:32   ` Andrii Nakryiko
2020-11-05 23:22     ` Daniel Xu
2020-11-05 23:31       ` Song Liu
2020-11-05 23:55         ` Daniel Xu

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