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Groups > linux.kernel > #1530461
| From | tip-bot for Wang Nan <tipbot@zytor.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [tip:perf/core] perf record: Fix segfault when running with suid and kptr_restrict is 1 |
| Date | 2016-11-25 18:30 +0100 |
| Message-ID | <sHstY-3tw-33@gated-at.bofh.it> (permalink) |
| References | <sDDeh-8kE-17@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Commit-ID: 3dbe46c5245f61328797738c6a0a6cd4bf921f61 Gitweb: http://git.kernel.org/tip/3dbe46c5245f61328797738c6a0a6cd4bf921f61 Author: Wang Nan <wangnan0@huawei.com> AuthorDate: Tue, 15 Nov 2016 04:05:45 +0000 Committer: Arnaldo Carvalho de Melo <acme@redhat.com> CommitDate: Fri, 25 Nov 2016 11:11:10 -0300 perf record: Fix segfault when running with suid and kptr_restrict is 1 Before this patch perf panics if kptr_restrict is set to 1 and perf is owned by root with suid set: $ whoami wangnan $ ls -l ./perf -rwsr-xr-x 1 root root 19781908 Sep 21 19:29 /home/wangnan/perf $ cat /proc/sys/kernel/kptr_restrict 1 $ cat /proc/sys/kernel/perf_event_paranoid -1 $ ./perf record -a Segmentation fault (core dumped) $ The reason is that perf assumes it is allowed to read kptr from /proc/kallsyms when euid is root, but in fact the kernel doesn't allow reading kptr when euid and uid do not match with each other: $ cp /bin/cat . $ sudo chown root:root ./cat $ sudo chmod u+s ./cat $ cat /proc/kallsyms | grep do_fork 0000000000000000 T _do_fork <--- kptr is hidden even euid is root $ sudo cat /proc/kallsyms | grep do_fork ffffffff81080230 T _do_fork See lib/vsprintf.c for kernel side code. This patch fixes this problem by checking both uid and euid. Signed-off-by: Wang Nan <wangnan0@huawei.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexei Starovoitov <ast@fb.com> Cc: He Kuang <hekuang@huawei.com> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/20161115040617.69788-3-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- tools/perf/util/symbol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index aecff69..420ada9 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -1962,7 +1962,7 @@ static bool symbol__read_kptr_restrict(void) char line[8]; if (fgets(line, sizeof(line), fp) != NULL) - value = (geteuid() != 0) ? + value = ((geteuid() != 0) || (getuid() != 0)) ? (atoi(line) != 0) : (atoi(line) == 2);
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[PATCH 00/34] perf clang: Builtin clang and perfhook support Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
[PATCH 21/34] perf clang: Pass CFLAGS to builtin clang Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
[PATCH 33/34] perf clang builtin: Define hook helpers by default Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
[PATCH 28/34] perf clang jit: Access BPF map Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
[PATCH 16/34] perf clang: Allow passing CFLAGS to builtin clang Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
[PATCH 23/34] perf clang jit: Insignt BPF and JIT functions in a Module Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
[PATCH 02/34] perf record: Fix segfault when running with suid and kptr_restrict is 1 Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
[tip:perf/core] perf record: Fix segfault when running with suid and kptr_restrict is 1 tip-bot for Wang Nan <tipbot@zytor.com> - 2016-11-25 18:30 +0100
[PATCH 06/34] tools lib bpf: Add private field for bpf_object Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
[PATCH 03/34] tools perf: Add missing struct defeinition in probe_event.h Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[tip:perf/core] perf tools: Add missing struct definition in probe_event.h tip-bot for Wang Nan <tipbot@zytor.com> - 2016-11-25 18:30 +0100
[PATCH 01/34] perf tools: Fix kernel version error in ubuntu Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[tip:perf/core] perf tools: Fix kernel version error in ubuntu tip-bot for Wang Nan <tipbot@zytor.com> - 2016-11-25 18:30 +0100
[PATCH 24/34] perf clang jit: add PerfModule::doJIT to JIT perfhook functions Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 30/34] perf clang: Link BPF functions declaration into perf Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 11/34] tools build: Add feature detection for LLVM Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 32/34] perf clang: Include helpers to BPF scripts Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 05/34] tools lib bpf: Add missing bpf map functions Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
Re: [PATCH 05/34] tools lib bpf: Add missing bpf map functions "Wangnan (F)" <wangnan0@huawei.com> - 2016-11-17 04:30 +0100
Re: [PATCH 05/34] tools lib bpf: Add missing bpf map functions Arnaldo Carvalho de Melo <acme@redhat.com> - 2016-11-25 15:50 +0100
[PATCH 31/34] perf clang: Declare BPF functions for BPF scripts automatically Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 29/34] perf clang jit: Allow jitted perf hook access BPF maps Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 34/34] perf clang git: Export getpid() to perf hook Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 09/34] perf tools: Pass context to perf hook functions Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 22/34] perf clang jit: Wrap llvm::Module using PerfModule Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 25/34] perf clang jit: Export functions for jitted code Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 20/34] perf clang: Pass full path to builtin clang Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 18/34] perf clang: Support compile IR to BPF object and add testcase Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 15/34] perf clang: Use real file system for #include Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 27/34] perf clang jit: Collect the lowest address in maps section as map_base Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 17/34] perf clang: Update test case to use real BPF script Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 13/34] perf build: Add clang and llvm compile and linking support Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 12/34] tools build: Add feature detection for clang Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 08/34] perf tools: Introduce perf hooks Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 07/34] tools lib bpf: Retrive bpf_map through offset of bpf_map_def Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 26/34] perf clang jit: Actually JIT and hook in bpf loader Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 14/34] perf clang: Add builtin clang support ant test case Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 10/34] perf llvm: Extract helpers in llvm-utils.c Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
[PATCH 19/34] perf clang: Compile BPF script use builtin clang support Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
Re: [PATCH 00/34] perf clang: Builtin clang and perfhook support "Wangnan (F)" <wangnan0@huawei.com> - 2016-11-15 05:40 +0100
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