linux-kernel - [PATCH] firewire: core: reduce stack usage in bus reset tasklet

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <tkrat.82fef6d14408ae6d@s5r6.in-berlin.de>
Date:	Fri, 28 Aug 2009 15:20:29 +0200 (CEST)
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	linux1394-devel@...ts.sourceforge.net
cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] firewire: core: reduce stack usage in bus reset tasklet

fw_compute_block_crc() used 1024 bytes of the kernel stack.  This
function is called
  - in process context when the local node's config ROM is updated,
  - in tasklet context of the bus reset handler.

Replace the stack-allocated buffer by a static buffer.
Serialize buffer accesses by a static local spinlock.

Signed-off-by: Stefan Richter <stefanr@...6.in-berlin.de>
---
 drivers/firewire/core-card.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

Index: linux-2.6.31-rc8/drivers/firewire/core-card.c
===================================================================
--- linux-2.6.31-rc8.orig/drivers/firewire/core-card.c
+++ linux-2.6.31-rc8/drivers/firewire/core-card.c
@@ -40,13 +40,19 @@
 
 int fw_compute_block_crc(u32 *block)
 {
-	__be32 be32_block[256];
+	static DEFINE_SPINLOCK(buffer_lock);
+	static __be32 buffer[256];
+	unsigned long flags;
 	int i, length;
 
+	spin_lock_irqsave(&buffer_lock, flags);
+
 	length = (*block >> 16) & 0xff;
 	for (i = 0; i < length; i++)
-		be32_block[i] = cpu_to_be32(block[i + 1]);
-	*block |= crc_itu_t(0, (u8 *) be32_block, length * 4);
+		buffer[i] = cpu_to_be32(block[i + 1]);
+	*block |= crc_itu_t(0, (u8 *)buffer, length * 4);
+
+	spin_unlock_irqrestore(&buffer_lock, flags);
 
 	return length;
 }

-- 
Stefan Richter
-=====-==--= =--- ===--
http://arcgraph.de/sr/

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/