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MDEV-39219: buffer overflow in PROXY protocol v1 header parsing #4881

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uwezkhan wants to merge 5 commits into from
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MDEV-39219: buffer overflow in PROXY protocol v1 header parsing #4881

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dd6ecac
Fix buffer overflow in PROXY protocol header parsing
uwezkhan Mar 30, 2026
78b7632
Updated
uwezkhan Apr 1, 2026
aaa9349
fix off-by-one buffer overflow in PROXY header parsing
uwezkhan Apr 1, 2026
85e3746
fix off-by-one buffer overflow in PROXY header parsing
uwezkhan Apr 1, 2026
fed0ac0
Merge branch 'header-overflow' of https://github.com/uwezkhan/server …
uwezkhan Apr 1, 2026
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8 changes: 4 additions & 4 deletions sql/proxy_protocol.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -174,7 +174,7 @@ bool has_proxy_protocol_header(NET *net)
*/
int parse_proxy_protocol_header(NET *net, proxy_peer_info *peer_info)
{
uchar hdr[MAX_PROXY_HEADER_LEN];
uchar hdr[MAX_PROXY_HEADER_LEN + 1];
size_t pos= 0;

DBUG_ASSERT(!net->compress);
Expand All @@ -195,12 +195,12 @@ int parse_proxy_protocol_header(NET *net, proxy_peer_info *peer_info)
if (have_v1_header)
{
/* Read until end of header (newline character)*/
while(pos < sizeof(hdr))
while(pos < sizeof(hdr) - 1)
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{
long len= (long)vio_read(vio, hdr + pos, 1);
if (len < 0)
if (len <= 0)
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return -1;
pos++;
pos += len;
if (hdr[pos-1] == '\n')
break;
}
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37 changes: 37 additions & 0 deletions tests/mysql_client_test.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20750,6 +20750,40 @@ static void test_proxy_header_ignore()
}


#ifndef EMBEDDED_LIBRARY
static void test_proxy_header_limits()
{
MYSQL *m;
char text_header[256];
const char *prefix = "PROXY TCP4 1.2.3.4 5.6.7.8 1234 5678";
size_t prefix_len;

myheader("test_proxy_header_limits");

/* Test maximum length PROXY header (256 bytes) to ensure no overflow */
memset(text_header, ' ', sizeof(text_header));

prefix_len = strlen(prefix);

memcpy(text_header, prefix, prefix_len);
text_header[sizeof(text_header) - 1] = '\n';

m = mysql_client_init(NULL);
DIE_UNLESS(m);

mysql_optionsv(m, MARIADB_OPT_PROXY_HEADER, text_header, sizeof(text_header));

if (mysql_real_connect(m, opt_host, "root", "", NULL, opt_port, opt_unix_socket, 0))
{
mysql_close(m);
}
else
{
/* Connection failure is acceptable, but server must remain stable */
}
}
#endif

static void test_proxy_header()
{
myheader("test_proxy_header");
Expand All @@ -20758,6 +20792,9 @@ static void test_proxy_header()
test_proxy_header_tcp("::ffff:192.0.2.1",2222);
test_proxy_header_localhost();
test_proxy_header_ignore();
#ifndef EMBEDDED_LIBRARY
test_proxy_header_limits();
#endif
}


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