From: Marcel Holtmann Date: Tue, 6 Mar 2007 21:12:00 +0000 (+0100) Subject: [PATCH] Fix buffer overflow in Omnikey CardMan 4040 driver (CVE-2007-0005) X-Git-Tag: v2.6.21-rc3~17 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=059819a41d4331316dd8ddcf977a24ab338f4300;p=linux-2.6 [PATCH] Fix buffer overflow in Omnikey CardMan 4040 driver (CVE-2007-0005) Based on a patch from Don Howard When calling write() with a buffer larger than 512 bytes, the driver's write buffer overflows, allowing to overwrite the EIP and execute arbitrary code with kernel privileges. In read(), there exists a similar problem, but coming from the device. A malicous or buggy device sending more than 512 bytes can overflow of the driver's read buffer, with the same effects as above. Signed-off-by: Marcel Holtmann Signed-off-by: Harald Welte Signed-off-by: Linus Torvalds --- diff --git a/drivers/char/pcmcia/cm4040_cs.c b/drivers/char/pcmcia/cm4040_cs.c index 0e82968c2f..f2e4ec4fd4 100644 --- a/drivers/char/pcmcia/cm4040_cs.c +++ b/drivers/char/pcmcia/cm4040_cs.c @@ -273,6 +273,7 @@ static ssize_t cm4040_read(struct file *filp, char __user *buf, DEBUGP(6, dev, "BytesToRead=%lu\n", bytes_to_read); min_bytes_to_read = min(count, bytes_to_read + 5); + min_bytes_to_read = min_t(size_t, min_bytes_to_read, READ_WRITE_BUFFER_SIZE); DEBUGP(6, dev, "Min=%lu\n", min_bytes_to_read); @@ -340,7 +341,7 @@ static ssize_t cm4040_write(struct file *filp, const char __user *buf, return 0; } - if (count < 5) { + if ((count < 5) || (count > READ_WRITE_BUFFER_SIZE)) { DEBUGP(2, dev, "<- cm4040_write buffersize=%Zd < 5\n", count); return -EIO; }