From 7c9f8861e6c9c839f913e49b98c3854daca18f27 Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Tue, 22 Apr 2008 16:38:23 -0500 Subject: stackprotector: use canary at end of stack to indicate overruns at oops time (Updated with a common max-stack-used checker that knows about the canary, as suggested by Joe Perches) Use a canary at the end of the stack to clearly indicate at oops time whether the stack has ever overflowed. This is a very simple implementation with a couple of drawbacks: 1) a thread may legitimately use exactly up to the last word on the stack -- but the chances of doing this and then oopsing later seem slim 2) it's possible that the stack usage isn't dense enough that the canary location could get skipped over -- but the worst that happens is that we don't flag the overrun -- though this happens fairly often in my testing :( With the code in place, an intentionally-bloated stack oops might do: BUG: unable to handle kernel paging request at ffff8103f84cc680 IP: [] update_curr+0x9a/0xa8 PGD 8063 PUD 0 Thread overran stack or stack corrupted Oops: 0000 [1] SMP CPU 0 ... ... unless the stack overrun is so bad that it corrupts some other thread. Signed-off-by: Eric Sandeen Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- include/linux/magic.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/magic.h') diff --git a/include/linux/magic.h b/include/linux/magic.h index 1fa0c2ce4dec..74e68e201166 100644 --- a/include/linux/magic.h +++ b/include/linux/magic.h @@ -42,4 +42,5 @@ #define FUTEXFS_SUPER_MAGIC 0xBAD1DEA #define INOTIFYFS_SUPER_MAGIC 0x2BAD1DEA +#define STACK_END_MAGIC 0x57AC6E9D #endif /* __LINUX_MAGIC_H__ */ -- cgit v1.2.3 From 1bcbf31337391a2f54ef6c1e8871c2de5944a7dc Mon Sep 17 00:00:00 2001 From: Qinghuang Feng Date: Thu, 15 Jan 2009 13:51:03 -0800 Subject: btrfs & squashfs: Move btrfs and squashfsto's magic number to Use the standard magic.h for btrfs and squashfs. Signed-off-by: Qinghuang Feng Cc: Phillip Lougher Cc: Chris Mason Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/btrfs/super.c | 2 +- fs/squashfs/squashfs_fs.h | 1 - fs/squashfs/super.c | 1 + include/linux/magic.h | 2 ++ 4 files changed, 4 insertions(+), 2 deletions(-) (limited to 'include/linux/magic.h') diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 0a14b495532f..7256cf242eb0 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -38,6 +38,7 @@ #include #include #include +#include #include "compat.h" #include "ctree.h" #include "disk-io.h" @@ -51,7 +52,6 @@ #include "export.h" #include "compression.h" -#define BTRFS_SUPER_MAGIC 0x9123683E static struct super_operations btrfs_super_ops; diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h index 6840da1bf21e..283daafc568e 100644 --- a/fs/squashfs/squashfs_fs.h +++ b/fs/squashfs/squashfs_fs.h @@ -26,7 +26,6 @@ #define SQUASHFS_CACHED_FRAGMENTS CONFIG_SQUASHFS_FRAGMENT_CACHE_SIZE #define SQUASHFS_MAJOR 4 #define SQUASHFS_MINOR 0 -#define SQUASHFS_MAGIC 0x73717368 #define SQUASHFS_START 0 /* size of metadata (inode and directory) blocks */ diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c index a0466d7467b2..071df5b5b491 100644 --- a/fs/squashfs/super.c +++ b/fs/squashfs/super.c @@ -35,6 +35,7 @@ #include #include #include +#include #include "squashfs_fs.h" #include "squashfs_fs_sb.h" diff --git a/include/linux/magic.h b/include/linux/magic.h index 439f6f3cb0c4..0b4df7eba852 100644 --- a/include/linux/magic.h +++ b/include/linux/magic.h @@ -10,11 +10,13 @@ #define SYSFS_MAGIC 0x62656572 #define SECURITYFS_MAGIC 0x73636673 #define TMPFS_MAGIC 0x01021994 +#define SQUASHFS_MAGIC 0x73717368 #define EFS_SUPER_MAGIC 0x414A53 #define EXT2_SUPER_MAGIC 0xEF53 #define EXT3_SUPER_MAGIC 0xEF53 #define XENFS_SUPER_MAGIC 0xabba1974 #define EXT4_SUPER_MAGIC 0xEF53 +#define BTRFS_SUPER_MAGIC 0x9123683E #define HPFS_SUPER_MAGIC 0xf995e849 #define ISOFS_SUPER_MAGIC 0x9660 #define JFFS2_SUPER_MAGIC 0x72b6 -- cgit v1.2.3