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syslog: Fix large messages (BZ#29536)
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The a583b6a change did not handle large messages that
would require a heap allocation correctly, where the message itself
is not take in consideration.

This patch fixes it and extend the tst-syslog to check for large
messages as well.

Checked on x86_64-linux-gnu.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
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@zatrazz
zatrazz committed Aug 30, 2022
1 parent ddcf5a9 commit 52a5be0
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Showing 2 changed files with 142 additions and 28 deletions.
18 changes: 11 additions & 7 deletions misc/syslog.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -193,28 +193,32 @@ __vsyslog_internal (int pri, const char *fmt, va_list ap,
int vl = __vsnprintf_internal (bufs + l, sizeof bufs - l, fmt, apc,
mode_flags);
if (0 <= vl && vl < sizeof bufs - l)
{
buf = bufs;
bufsize = l + vl;
}
buf = bufs;
bufsize = l + vl;

va_end (apc);
}

if (buf == NULL)
{
buf = malloc (l * sizeof (char));
buf = malloc ((bufsize + 1) * sizeof (char));
if (buf != NULL)
{
/* Tell the cancellation handler to free this buffer. */
clarg.buf = buf;

if (has_ts)
__snprintf (bufs, sizeof bufs,
__snprintf (buf, l + 1,
SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
else
__snprintf (bufs, sizeof bufs,
__snprintf (buf, l + 1,
SYSLOG_HEADER_WITHOUT_TS (pri, &msgoff));

va_list apc;
va_copy (apc, ap);
__vsnprintf_internal (buf + l, bufsize - l + 1, fmt, apc,
mode_flags);
va_end (apc);
}
else
{
Expand Down
152 changes: 131 additions & 21 deletions misc/tst-syslog.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,21 +68,19 @@ static const int priorities[] =
LOG_DEBUG
};

enum
{
ident_length = 64,
msg_length = 64
};
#define IDENT_LENGTH 64
#define MSG_LENGTH 1024

#define SYSLOG_MSG_BASE "syslog_message"
#define OPENLOG_IDENT "openlog_ident"
static char large_message[MSG_LENGTH];

struct msg_t
{
int priority;
int facility;
char ident[ident_length];
char msg[msg_length];
char ident[IDENT_LENGTH];
char msg[MSG_LENGTH];
pid_t pid;
};

Expand Down Expand Up @@ -147,6 +145,37 @@ check_syslog_message (const struct msg_t *msg, int msgnum, int options,
return true;
}

static void
send_syslog_large (int options)
{
int facility = LOG_USER;
int priority = LOG_INFO;

syslog (facility | priority, "%s %d %d", large_message, facility,
priority);
}

static void
send_vsyslog_large (int options)
{
int facility = LOG_USER;
int priority = LOG_INFO;

call_vsyslog (facility | priority, "%s %d %d", large_message, facility,
priority);
}

static bool
check_syslog_message_large (const struct msg_t *msg, int msgnum, int options,
pid_t pid)
{
TEST_COMPARE (msg->facility, LOG_USER);
TEST_COMPARE (msg->priority, LOG_INFO);
TEST_COMPARE_STRING (msg->msg, large_message);

return false;
}

static void
send_openlog (int options)
{
Expand Down Expand Up @@ -179,6 +208,17 @@ send_openlog (int options)
closelog ();
}

static void
send_openlog_large (int options)
{
/* Define a non-default IDENT and a not default facility. */
openlog (OPENLOG_IDENT, options, LOG_LOCAL0);

syslog (LOG_INFO, "%s %d %d", large_message, LOG_LOCAL0, LOG_INFO);

closelog ();
}

static bool
check_openlog_message (const struct msg_t *msg, int msgnum,
int options, pid_t pid)
Expand All @@ -189,7 +229,7 @@ check_openlog_message (const struct msg_t *msg, int msgnum,
int expected_priority = priorities[msgnum % array_length (priorities)];
TEST_COMPARE (msg->priority, expected_priority);

char expected_ident[ident_length];
char expected_ident[IDENT_LENGTH];
snprintf (expected_ident, sizeof (expected_ident), "%s%s%.0d%s:",
OPENLOG_IDENT,
options & LOG_PID ? "[" : "",
Expand All @@ -211,15 +251,38 @@ check_openlog_message (const struct msg_t *msg, int msgnum,
return true;
}

static bool
check_openlog_message_large (const struct msg_t *msg, int msgnum,
int options, pid_t pid)
{
char expected_ident[IDENT_LENGTH];
snprintf (expected_ident, sizeof (expected_ident), "%s%s%.0d%s:",
OPENLOG_IDENT,
options & LOG_PID ? "[" : "",
options & LOG_PID ? pid : 0,
options & LOG_PID ? "]" : "");

TEST_COMPARE_STRING (msg->ident, expected_ident);
TEST_COMPARE_STRING (msg->msg, large_message);
TEST_COMPARE (msg->priority, LOG_INFO);
TEST_COMPARE (msg->facility, LOG_LOCAL0);

return false;
}

static struct msg_t
parse_syslog_msg (const char *msg)
{
struct msg_t r = { .pid = -1 };
int number;

#define STRINPUT(size) XSTRINPUT(size)
#define XSTRINPUT(size) "%" # size "s"

/* The message in the form:
<179>Apr 8 14:51:19 tst-syslog: syslog message 176 3 */
int n = sscanf (msg, "<%3d>%*s %*d %*d:%*d:%*d %32s %64s %*d %*d",
<179>Apr 8 14:51:19 tst-syslog: message 176 3 */
int n = sscanf (msg, "<%3d>%*s %*d %*d:%*d:%*d " STRINPUT(IDENT_LENGTH)
" " STRINPUT(MSG_LENGTH) " %*d %*d",
&number, r.ident, r.msg);
TEST_COMPARE (n, 3);

Expand All @@ -246,7 +309,7 @@ parse_syslog_console (const char *msg)

/* The message in the form:
openlog_ident: syslog_message 128 0 */
int n = sscanf (msg, "%32s %64s %d %d",
int n = sscanf (msg, STRINPUT(IDENT_LENGTH) " " STRINPUT(MSG_LENGTH) " %d %d",
r.ident, r.msg, &facility, &priority);
TEST_COMPARE (n, 4);

Expand Down Expand Up @@ -281,7 +344,7 @@ check_syslog_udp (void (*syslog_send)(int), int options,
int msgnum = 0;
while (1)
{
char buf[512];
char buf[2048];
size_t l = xrecvfrom (server_udp, buf, sizeof (buf), 0,
(struct sockaddr *) &addr, &addrlen);
buf[l] = '\0';
Expand Down Expand Up @@ -325,7 +388,7 @@ check_syslog_tcp (void (*syslog_send)(int), int options,

int client_tcp = xaccept (server_tcp, NULL, NULL);

char buf[512], *rb = buf;
char buf[2048], *rb = buf;
size_t rbl = sizeof (buf);
size_t prl = 0; /* Track the size of the partial record. */
int msgnum = 0;
Expand Down Expand Up @@ -393,20 +456,34 @@ check_syslog_console_read (FILE *fp)
}

static void
check_syslog_console (void)
check_syslog_console_read_large (FILE *fp)
{
char buf[2048];
TEST_VERIFY (fgets (buf, sizeof (buf), fp) != NULL);
struct msg_t msg = parse_syslog_console (buf);

TEST_COMPARE_STRING (msg.ident, OPENLOG_IDENT ":");
TEST_COMPARE_STRING (msg.msg, large_message);
TEST_COMPARE (msg.priority, LOG_INFO);
TEST_COMPARE (msg.facility, LOG_LOCAL0);
}

static void
check_syslog_console (void (*syslog_send)(int),
void (*syslog_check)(FILE *fp))
{
xmkfifo (_PATH_CONSOLE, 0666);

pid_t sender_pid = xfork ();
if (sender_pid == 0)
{
send_openlog (LOG_CONS);
syslog_send (LOG_CONS);
_exit (0);
}

{
FILE *fp = xfopen (_PATH_CONSOLE, "r+");
check_syslog_console_read (fp);
syslog_check (fp);
xfclose (fp);
}

Expand All @@ -425,16 +502,28 @@ send_openlog_callback (void *clousure)
}

static void
check_syslog_perror (void)
send_openlog_callback_large (void *clousure)
{
int options = *(int *) clousure;
send_openlog_large (options);
}

static void
check_syslog_perror (bool large)
{
struct support_capture_subprocess result;
result = support_capture_subprocess (send_openlog_callback,
result = support_capture_subprocess (large
? send_openlog_callback_large
: send_openlog_callback,
&(int){LOG_PERROR});

FILE *mfp = fmemopen (result.err.buffer, result.err.length, "r");
if (mfp == NULL)
FAIL_EXIT1 ("fmemopen: %m");
check_syslog_console_read (mfp);
if (large)
check_syslog_console_read_large (mfp);
else
check_syslog_console_read (mfp);
xfclose (mfp);

support_capture_subprocess_check (&result, "tst-openlog-child", 0,
Expand Down Expand Up @@ -462,10 +551,31 @@ do_test (void)
check_syslog_tcp (send_openlog, LOG_PID, check_openlog_message);

/* Check the LOG_CONS option. */
check_syslog_console ();
check_syslog_console (send_openlog, check_syslog_console_read);

/* Check the LOG_PERROR option. */
check_syslog_perror ();
check_syslog_perror (false);

/* Similar tests as before, but with a large message to trigger the
syslog path that uses dynamically allocated memory. */
memset (large_message, 'a', sizeof large_message - 1);
large_message[sizeof large_message - 1] = '\0';

check_syslog_udp (send_syslog_large, 0, check_syslog_message_large);
check_syslog_tcp (send_syslog_large, 0, check_syslog_message_large);

check_syslog_udp (send_vsyslog_large, 0, check_syslog_message_large);
check_syslog_tcp (send_vsyslog_large, 0, check_syslog_message_large);

check_syslog_udp (send_openlog_large, 0, check_openlog_message_large);
check_syslog_tcp (send_openlog_large, 0, check_openlog_message_large);

check_syslog_udp (send_openlog_large, LOG_PID, check_openlog_message_large);
check_syslog_tcp (send_openlog_large, LOG_PID, check_openlog_message_large);

check_syslog_console (send_openlog_large, check_syslog_console_read_large);

check_syslog_perror (true);

return 0;
}
Expand Down

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