Messages in this thread Patch in this message | | | Date | Fri, 17 Aug 2012 04:03:17 +0100 | From | Ben Hutchings <> | Subject | [ 34/37] s390/compat: fix mmap compat system calls |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: Heiko Carstens <heiko.carstens@de.ibm.com>
commit e85871218513c54f7dfdb6009043cb638f2fecbe upstream.
The native 31 bit and the compat behaviour for the mmap system calls differ:
In native 31 bit mode the passed in address for the mmap system call will be unmodified passed to sys_mmap_pgoff(). In compat mode however the passed in address will be modified with compat_ptr() which masks out the most significant bit.
The result is that in native 31 bit mode each mmap request (with MAP_FIXED) will fail where the most significat bit is set, while in compat mode it may succeed.
This odd behaviour was introduced with d3815898 "[S390] mmap: add missing compat_ptr conversion to both mmap compat syscalls".
To restore a consistent behaviour accross native and compat mode this patch functionally reverts the above mentioned commit.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- arch/s390/kernel/compat_linux.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c index d122508..f606d93 100644 --- a/arch/s390/kernel/compat_linux.c +++ b/arch/s390/kernel/compat_linux.c @@ -620,7 +620,6 @@ asmlinkage unsigned long old32_mmap(struct mmap_arg_struct_emu31 __user *arg) return -EFAULT; if (a.offset & ~PAGE_MASK) return -EINVAL; - a.addr = (unsigned long) compat_ptr(a.addr); return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, a.offset >> PAGE_SHIFT); } @@ -631,7 +630,6 @@ asmlinkage long sys32_mmap2(struct mmap_arg_struct_emu31 __user *arg) if (copy_from_user(&a, arg, sizeof(a))) return -EFAULT; - a.addr = (unsigned long) compat_ptr(a.addr); return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, a.offset); }
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