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authorAlexandra Kossovsky <Alexandra.Kossovsky@oktetlabs.ru>2005-11-20 13:41:59 -0800
committerDavid S. Miller <davem@davemloft.net>2005-11-20 13:41:59 -0800
commit4909724b5dee8fb7c52bbe90afa40c65b17be9eb (patch)
tree7611a0f01ff0b0a1389928683b4223c160123d2a
parentfb0d366b0803571f06a5b838f02c6706fc287995 (diff)
[COMPAT] net: SIOCGIFCONF data corruption
From: Alexandra Kossovsky <Alexandra.Kossovsky@oktetlabs.ru> From http://bugzilla.kernel.org/show_bug.cgi?id=4746 There is user data corruption when using ioctl(SIOCGIFCONF) in 32-bit application running amd64 kernel. I do not think that this problem is exploitable, but any data corruption may lead to security problems. Following code demonstrates the problem #include <stdint.h> #include <stdio.h> #include <sys/time.h> #include <sys/socket.h> #include <net/if.h> #include <sys/ioctl.h> char buf[256]; main() { int s = socket(AF_INET, SOCK_DGRAM, 0); struct ifconf req; int i; req.ifc_buf = buf; req.ifc_len = 41; printf("Result %d\n", ioctl(s, SIOCGIFCONF, &req)); printf("Len %d\n", req.ifc_len); for (i = 41; i < 256; i++) if (buf[i] != 0) printf("Byte %d is corrupted\n", i); } Steps to reproduce: Compile the code above into 32-bit elf and run it. You'll get Result 0 Len 32 Byte 48 is corrupted Byte 52 is corrupted Byte 53 is corrupted Byte 54 is corrupted Byte 55 is corrupted Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--fs/compat_ioctl.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index 31b7efd94d66..43a2508ac696 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -686,7 +686,8 @@ static int dev_ifconf(unsigned int fd, unsigned int cmd, unsigned long arg)
ifr = ifc.ifc_req;
ifr32 = compat_ptr(ifc32.ifcbuf);
- for (i = 0, j = 0; i < ifc32.ifc_len && j < ifc.ifc_len;
+ for (i = 0, j = 0;
+ i + sizeof (struct ifreq32) < ifc32.ifc_len && j < ifc.ifc_len;
i += sizeof (struct ifreq32), j += sizeof (struct ifreq)) {
if (copy_in_user(ifr32, ifr, sizeof (struct ifreq32)))
return -EFAULT;
@@ -702,10 +703,7 @@ static int dev_ifconf(unsigned int fd, unsigned int cmd, unsigned long arg)
i = ((i / sizeof(struct ifreq)) * sizeof(struct ifreq32));
ifc32.ifc_len = i;
} else {
- if (i <= ifc32.ifc_len)
- ifc32.ifc_len = i;
- else
- ifc32.ifc_len = i - sizeof (struct ifreq32);
+ ifc32.ifc_len = i;
}
if (copy_to_user(compat_ptr(arg), &ifc32, sizeof(struct ifconf32)))
return -EFAULT;