Messages in this thread Patch in this message | | | Date | Thu, 20 Apr 2006 21:39:51 -0700 | From | Greg KH <> | Subject | [patch 22/22] Add more prevent_tail_call() |
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From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
[PATCH] Add more prevent_tail_call()
Those also break userland regs like following.
00000000 <sys_chown16>: 0: 0f b7 44 24 0c movzwl 0xc(%esp),%eax 5: 83 ca ff or $0xffffffff,%edx 8: 0f b7 4c 24 08 movzwl 0x8(%esp),%ecx d: 66 83 f8 ff cmp $0xffffffff,%ax 11: 0f 44 c2 cmove %edx,%eax 14: 66 83 f9 ff cmp $0xffffffff,%cx 18: 0f 45 d1 cmovne %ecx,%edx 1b: 89 44 24 0c mov %eax,0xc(%esp) 1f: 89 54 24 08 mov %edx,0x8(%esp) 23: e9 fc ff ff ff jmp 24 <sys_chown16+0x24>
where the tailcall at the end overwrites the incoming stack-frame.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/uid16.c | 59 ++++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 46 insertions(+), 13 deletions(-)
--- linux-2.6.16.9.orig/kernel/uid16.c +++ linux-2.6.16.9/kernel/uid16.c @@ -20,43 +20,67 @@ asmlinkage long sys_chown16(const char __user * filename, old_uid_t user, old_gid_t group) { - return sys_chown(filename, low2highuid(user), low2highgid(group)); + long ret = sys_chown(filename, low2highuid(user), low2highgid(group)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_lchown16(const char __user * filename, old_uid_t user, old_gid_t group) { - return sys_lchown(filename, low2highuid(user), low2highgid(group)); + long ret = sys_lchown(filename, low2highuid(user), low2highgid(group)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_fchown16(unsigned int fd, old_uid_t user, old_gid_t group) { - return sys_fchown(fd, low2highuid(user), low2highgid(group)); + long ret = sys_fchown(fd, low2highuid(user), low2highgid(group)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_setregid16(old_gid_t rgid, old_gid_t egid) { - return sys_setregid(low2highgid(rgid), low2highgid(egid)); + long ret = sys_setregid(low2highgid(rgid), low2highgid(egid)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_setgid16(old_gid_t gid) { - return sys_setgid(low2highgid(gid)); + long ret = sys_setgid(low2highgid(gid)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_setreuid16(old_uid_t ruid, old_uid_t euid) { - return sys_setreuid(low2highuid(ruid), low2highuid(euid)); + long ret = sys_setreuid(low2highuid(ruid), low2highuid(euid)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_setuid16(old_uid_t uid) { - return sys_setuid(low2highuid(uid)); + long ret = sys_setuid(low2highuid(uid)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_setresuid16(old_uid_t ruid, old_uid_t euid, old_uid_t suid) { - return sys_setresuid(low2highuid(ruid), low2highuid(euid), - low2highuid(suid)); + long ret = sys_setresuid(low2highuid(ruid), low2highuid(euid), + low2highuid(suid)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_getresuid16(old_uid_t __user *ruid, old_uid_t __user *euid, old_uid_t __user *suid) @@ -72,8 +96,11 @@ asmlinkage long sys_getresuid16(old_uid_ asmlinkage long sys_setresgid16(old_gid_t rgid, old_gid_t egid, old_gid_t sgid) { - return sys_setresgid(low2highgid(rgid), low2highgid(egid), - low2highgid(sgid)); + long ret = sys_setresgid(low2highgid(rgid), low2highgid(egid), + low2highgid(sgid)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_getresgid16(old_gid_t __user *rgid, old_gid_t __user *egid, old_gid_t __user *sgid) @@ -89,12 +116,18 @@ asmlinkage long sys_getresgid16(old_gid_ asmlinkage long sys_setfsuid16(old_uid_t uid) { - return sys_setfsuid(low2highuid(uid)); + long ret = sys_setfsuid(low2highuid(uid)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } asmlinkage long sys_setfsgid16(old_gid_t gid) { - return sys_setfsgid(low2highgid(gid)); + long ret = sys_setfsgid(low2highgid(gid)); + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; } static int groups16_to_user(old_gid_t __user *grouplist, -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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