Hi Luiz,
On 10/02/2017 05:03 PM, Luiz Augusto von Dentz wrote:
> Hi Eramoto,
>
> On Fri, Sep 29, 2017 at 7:40 AM, ERAMOTO Masaya
> <eramoto.masaya@xxxxxxxxxxxxxx> wrote:
>> If btmon and btproyx use a unix socket, which has a long pathname,
>> then the buffer overflows occur as below:
>>
>> *** strcpy_chk: buffer overflow detected ***: program terminated
>> at 0x4C3085C: ??? (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> by 0x4C34E46: __strcpy_chk (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> by 0x4084FE: strcpy (string3.h:110)
>> by 0x4084FE: control_server (control.c:1148)
>> by 0x4029E9: main (main.c:144)
>>
>> *** strcpy_chk: buffer overflow detected ***: program terminated
>> at 0x4C3085C: ??? (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> by 0x4C34E46: __strcpy_chk (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> by 0x401B74: strcpy (string3.h:110)
>> by 0x401B74: open_unix (btproxy.c:625)
>> by 0x401B74: main (btproxy.c:901)
>
> Lets have the fixes separately, one for btmon and another for btproxy.
>
>> This patch also gives an error and stops running when parsing command-line
>> arguments, if the unix socket pathname is too long.
>> ---
>> monitor/control.c | 7 ++++++-
>> monitor/main.c | 7 +++++++
>> tools/btproxy.c | 17 ++++++++++++++---
>> 3 files changed, 27 insertions(+), 4 deletions(-)
>>
>> diff --git a/monitor/control.c b/monitor/control.c
>> index 9bbdc37..5a1b5e2 100644
>> --- a/monitor/control.c
>> +++ b/monitor/control.c
>> @@ -1130,6 +1130,7 @@ static int server_fd = -1;
>> void control_server(const char *path)
>> {
>> struct sockaddr_un addr;
>> + size_t len;
>> int fd;
>>
>> if (server_fd >= 0)
>> @@ -1143,9 +1144,13 @@ void control_server(const char *path)
>> return;
>> }
>>
>> + len = strlen(path);
>> + if (len > sizeof(addr.sun_path) - 1)
>> + len = sizeof(addr.sun_path) - 1;
>> +
>
> Should we actually fail here or you are truncating the path on btproxy?
We should fail in advance of unlink() since above control_server removes the
user-specified file and creates the truncated file, which is not user-specified,
thus will confuse users.
>
>> memset(&addr, 0, sizeof(addr));
>> addr.sun_family = AF_UNIX;
>> - strcpy(addr.sun_path, path);
>> + strncpy(addr.sun_path, path, len);
>>
>> if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
>> perror("Failed to bind server socket");
>> diff --git a/monitor/main.c b/monitor/main.c
>> index b4e9a6a..68ae821 100644
>> --- a/monitor/main.c
>> +++ b/monitor/main.c
>> @@ -31,6 +31,7 @@
>> #include <stdlib.h>
>> #include <string.h>
>> #include <getopt.h>
>> +#include <sys/un.h>
>>
>> #include "src/shared/mainloop.h"
>> #include "src/shared/tty.h"
>> @@ -114,6 +115,7 @@ int main(int argc, char *argv[])
>>
>> for (;;) {
>> int opt;
>> + struct sockaddr_un addr;
>>
>> opt = getopt_long(argc, argv, "d:r:w:a:s:p:i:tTSAE:vh",
>> main_options, NULL);
>> @@ -141,6 +143,11 @@ int main(int argc, char *argv[])
>> analyze_path = optarg;
>> break;
>> case 's':
>> + if (strlen(optarg) >
>> + sizeof(addr.sun_path) - 1) {
>> + fprintf(stderr, "Socket too long\n");
>> + return EXIT_FAILURE;
>
> If this would fail here Im no sure what is the point of the check on
> control_server? Btw, the message should probably be "Socket name too
> long".
I want to add these redundant checks
- to prevent the regression if reusing control_server()/open_unix()
in the future
and
- to immediately stop running when parsing command-line arguments.
If we should add the check when reusing control_server()/open_unix(),
I remove it and send patches.
Regards,
Eramoto
>
>> + }
>> control_server(optarg);
>> break;
>> case 'p':
>> diff --git a/tools/btproxy.c b/tools/btproxy.c
>> index f06661d..abe9ef8 100644
>> --- a/tools/btproxy.c
>> +++ b/tools/btproxy.c
>> @@ -610,6 +610,7 @@ static void server_callback(int fd, uint32_t events, void *user_data)
>> static int open_unix(const char *path)
>> {
>> struct sockaddr_un addr;
>> + size_t len;
>> int fd;
>>
>> unlink(path);
>> @@ -620,9 +621,13 @@ static int open_unix(const char *path)
>> return -1;
>> }
>>
>> + len = strlen(path);
>> + if (len > sizeof(addr.sun_path) - 1)
>> + len = sizeof(addr.sun_path) - 1;
>> +
>> memset(&addr, 0, sizeof(addr));
>> addr.sun_family = AF_UNIX;
>> - strcpy(addr.sun_path, path);
>> + strncpy(addr.sun_path, path, len);
>>
>> if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
>> perror("Failed to bind Unix server socket");
>> @@ -797,9 +802,15 @@ int main(int argc, char *argv[])
>> server_address = "0.0.0.0";
>> break;
>> case 'u':
>> - if (optarg)
>> + if (optarg) {
>> + struct sockaddr_un addr;
>> unix_path = optarg;
>> - else
>> + if (strlen(unix_path) >
>> + sizeof(addr.sun_path) - 1) {
>> + fprintf(stderr, "Path too long\n");
>> + return EXIT_FAILURE;
>> + }
>> + } else
>> unix_path = "/tmp/bt-server-bredr";
>> break;
>> case 'p':
>> --
>> 2.7.4
>>
>> --
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>
>
>
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