From: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
To: linux-modules <linux-modules@vger.kernel.org>
Cc: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>,
bjorn.andersson@linaro.org, afaerber@suse.de
Subject: Re: [PATCH v1 2/2] depmod: ignore related modules in depmod_report_cycles
Date: Wed, 09 Nov 2016 04:59:33 +0200 [thread overview]
Message-ID: <xunyk2cdiciy.fsf@redhat.com> (raw)
In-Reply-To: <CAKi4VAKh0R-RN1j=Eum3wKtQ434D_7uBj1EGwzGCBrEB0qFkTg@mail.gmail.com> (Lucas De Marchi's message of "Tue, 8 Nov 2016 22:40:20 -0200")
Hi!
It may require more serious refactoring, since there is a problem with the
approach of path recording. I can get wrong output, for example, for the
following graph:
/*
mod6 -> mod7 -> mod8 -> mod9
^ | |
--------------- |
| |
-----------------------
*/
depmod: ERROR: Cycle detected: mod7 -> mod8 -> mod9 -> mod6 -> mod7
depmod: ERROR: Cycle detected: mod6 -> mod6
depmod: ERROR: Found 5 modules in dependency cycles!
The problem is that the path is recorded "globally", not per vertex, and
"wrong" mod6 is compared in "loop == m".
>>>>> On Tue, 8 Nov 2016 22:40:20 -0200, Lucas De Marchi wrote:
> On Tue, Nov 8, 2016 at 2:45 PM, Mian Yousaf Kaukab
> <yousaf.kaukab@suse.com> wrote:
>> Only print actual cyclic dependencies. Print count of all the modules
>> in cyclic dependency at the end of the function so that dependent
>> modules which are not in cyclic chain can be ignored.
>>
>> Printing dependent modules which are not in cyclic chain causes buffer
>> overflow as m->modnamesz is not included in buffer size calculations
>> (loop == m is never true). This buffer overflow causes kmod to crash.
>>
>> Update depmod test to reflect the change as well.
>>
>> Reported-by: Andreas Färber <afaerber@suse.de>
>> Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
>> ---
>> Change-log:
>> v1: Keep the old output stings. Only change their order
>> Add test case to reproduce the problem
>>
>> .../rootfs-pristine/test-depmod/detect-loop/correct.txt | 2 +-
>> tools/depmod.c | 13 ++++++++++++-
>> 2 files changed, 13 insertions(+), 2 deletions(-)
>>
>> diff --git a/testsuite/rootfs-pristine/test-depmod/detect-loop/correct.txt b/testsuite/rootfs-pristine/test-depmod/detect-loop/correct.txt
>> index 4eb26df..01ecb89 100644
>> --- a/testsuite/rootfs-pristine/test-depmod/detect-loop/correct.txt
>> +++ b/testsuite/rootfs-pristine/test-depmod/detect-loop/correct.txt
>> @@ -1,3 +1,3 @@
>> -depmod: ERROR: Found 5 modules in dependency cycles!
>> depmod: ERROR: Cycle detected: mod_loop_d -> mod_loop_e -> mod_loop_d
>> depmod: ERROR: Cycle detected: mod_loop_b -> mod_loop_c -> mod_loop_a -> mod_loop_b
>> +depmod: ERROR: Found 5 modules in dependency cycles!
>> diff --git a/tools/depmod.c b/tools/depmod.c
>> index ad01f66..f2b370f 100644
>> --- a/tools/depmod.c
>> +++ b/tools/depmod.c
>> @@ -1456,7 +1456,7 @@ static void depmod_report_cycles(struct depmod *depmod, uint16_t n_mods,
>> {
>> const char sep[] = " -> ";
>> int ir = 0;
>> - ERR("Found %u modules in dependency cycles!\n", n_roots);
>> + int num_cyclic = 0;
>>
>> while (n_roots > 0) {
>> int is, ie;
>> @@ -1491,6 +1491,7 @@ static void depmod_report_cycles(struct depmod *depmod, uint16_t n_mods,
>> if (m->visited) {
>> int i, n = 0, sz = 0;
>> char *buf;
>> + bool is_cyclic = false;
>>
>> for (i = ie - 1; i >= 0; i--) {
>> struct mod *loop = depmod->modules.array[edges[i]];
>> @@ -1498,9 +1499,17 @@ static void depmod_report_cycles(struct depmod *depmod, uint16_t n_mods,
>> n++;
>> if (loop == m) {
>> sz += loop->modnamesz - 1;
>> + is_cyclic = true;
>> break;
>> }
>> }
>> + /* Current module not found in dependency list.
>> + * Must be a related module. Ignore it.
>> + */
>> + if (!is_cyclic)
>> + continue;
>> +
>> + num_cyclic += n;
>>
>> buf = malloc(sz + n * strlen(sep) + 1);
>> sz = 0;
>> @@ -1538,6 +1547,8 @@ static void depmod_report_cycles(struct depmod *depmod, uint16_t n_mods,
>> }
>> }
>> }
>> +
>> + ERR("Found %d modules in dependency cycles!\n", num_cyclic);
>> }
> thanks, much better now.
> Applied.
--
WBR,
Yauheni Kaliuta
next prev parent reply other threads:[~2016-11-09 2:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-08 16:45 [PATCH v1 1/2] testsuite: depmod: add module dependency outside cyclic chain Mian Yousaf Kaukab
2016-11-08 16:45 ` [PATCH v1 2/2] depmod: ignore related modules in depmod_report_cycles Mian Yousaf Kaukab
2016-11-09 0:40 ` Lucas De Marchi
2016-11-09 2:59 ` Yauheni Kaliuta [this message]
2016-11-09 9:17 ` Mian Yousaf Kaukab
2016-11-09 11:23 ` Yauheni Kaliuta
2016-11-11 11:43 ` [PATCH RFC 0/3] Proposal for cycles handling Yauheni Kaliuta
2016-11-11 11:43 ` [PATCH RFC 2/3] libkmod: list: export list handling functions Yauheni Kaliuta
2017-02-13 8:05 ` Lucas De Marchi
2017-02-20 14:22 ` Yauheni Kaliuta
2017-02-22 5:26 ` Lucas De Marchi
2017-02-22 9:41 ` [PATCH v3 0/2] Proposal for cycles handling Yauheni Kaliuta
2017-02-22 9:41 ` [PATCH v3 1/2] testsuite: depmod: check netsted loops reporting Yauheni Kaliuta
2017-02-22 9:41 ` [PATCH v3 2/2] depmod: handle nested loops Yauheni Kaliuta
2017-02-23 22:30 ` Lucas De Marchi
2016-11-11 11:43 ` [PATCH RFC 3/3] " Yauheni Kaliuta
2017-02-13 8:30 ` Lucas De Marchi
2017-02-20 14:16 ` Yauheni Kaliuta
2017-02-13 8:16 ` [PATCH RFC 0/3] Proposal for cycles handling Lucas De Marchi
2017-02-13 9:56 ` Yauheni Kaliuta
2017-02-13 8:32 ` Lucas De Marchi
2017-02-20 14:18 ` [PATCH RFC v2 0/2] " Yauheni Kaliuta
2017-02-20 14:18 ` [PATCH RFC v2 1/2] testsuite: depmod: check netsted loops reporting Yauheni Kaliuta
2017-02-20 14:19 ` [PATCH RFC v2 2/2] depmod: handle nested loops Yauheni Kaliuta
2016-11-09 0:29 ` [PATCH v1 1/2] testsuite: depmod: add module dependency outside cyclic chain Lucas De Marchi
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