netdev - [BUG] 2.6.37-rc5 Memory leak in net/ipv4/udp.c

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Date:	Fri, 17 Dec 2010 11:18:05 +0100
From:	Lothar Waßmann <LW@...O-electronics.de>
To:	netdev@...r.kernel.org
Subject: [BUG] 2.6.37-rc5 Memory leak in net/ipv4/udp.c

Hi,

the kernel memory leak detector spews the message:
|kmemleak: 2 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
cat /sys/kernel/debug/kmemleak
|unreferenced object 0xc7a1c000 (size 5120):
|  comm "swapper", pid 1, jiffies 4294937513 (age 2320.120s)
|  hex dump (first 32 bytes):
|    aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
|    aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
|  backtrace:
|    [<c00112b8>] alloc_large_system_hash+0x188/0x224
|    [<c001be14>] udp_table_init+0x44/0x180
|    [<c001bf64>] udp_init+0x14/0x78
|    [<c001c620>] inet_init+0x138/0x240
|    [<c0030368>] do_one_initcall+0x58/0x1a8
|    [<c00083c8>] kernel_init+0x98/0x14c
|    [<c0037714>] kernel_thread_exit+0x0/0x8
|    [<ffffffff>] 0xffffffff
|unreferenced object 0xc7a26000 (size 5120):
|  comm "swapper", pid 1, jiffies 4294937513 (age 2320.130s)
|  hex dump (first 32 bytes):
|    aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
|    aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
|  backtrace:
|    [<c00112b8>] alloc_large_system_hash+0x188/0x224
|    [<c001be14>] udp_table_init+0x44/0x180
|    [<c001bff0>] udplite4_register+0x10/0x94
|    [<c001c624>] inet_init+0x13c/0x240
|    [<c0030368>] do_one_initcall+0x58/0x1a8
|    [<c00083c8>] kernel_init+0x98/0x14c
|    [<c0037714>] kernel_thread_exit+0x0/0x8
|    [<ffffffff>] 0xffffffff

The offending code in net/ipv4/udp.c is:
|void __init udp_table_init(struct udp_table *table, const char *name)
|{
|	unsigned int i;
|
|	if (!CONFIG_BASE_SMALL)
|		table->hash = alloc_large_system_hash(name,
|			2 * sizeof(struct udp_hslot),
|			uhash_entries,
|			21, /* one slot per 2 MB */
|			0,
|			&table->log,
|			&table->mask,
|			64 * 1024);
|	/*
|	 * Make sure hash table has the minimum size
|	 */
|	if (CONFIG_BASE_SMALL || table->mask < UDP_HTABLE_SIZE_MIN - 1) {
|		table->hash = kmalloc(UDP_HTABLE_SIZE_MIN *
|				      2 * sizeof(struct udp_hslot), GFP_KERNEL);
In case of !CONFIG_BASE_SMALL and 'table->mask < UDP_HTABLE_SIZE_MIN - 1)'
the memory allocated in the previous if clause becomes inacessible!

Shouldn't this be:
|	if (!CONFIG_BASE_SMALL && table->mask >= UDP_HTABLE_SIZE_MIN - 1) {
|		table->hash = alloc_large_system_hash(name,
|			2 * sizeof(struct udp_hslot),
|			uhash_entries,
|			21, /* one slot per 2 MB */
|			0,
|			&table->log,
|			&table->mask,
|			64 * 1024);
|	} else {
|		table->hash = kmalloc(UDP_HTABLE_SIZE_MIN *
|				      2 * sizeof(struct udp_hslot), GFP_KERNEL);
[...]



Lothar Waßmann
-- 
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