parisc: use initializer for struct vm_unmapped_area_info

Future changes will need to add a new member to struct
vm_unmapped_area_info.  This would cause trouble for any call site that
doesn't initialize the struct.  Currently every caller sets each member
manually, so if new members are added they will be uninitialized and the
core code parsing the struct will see garbage in the new member.

It could be possible to initialize the new member manually to 0 at each
call site.  This and a couple other options were discussed, and a working
consensus (see links) was that in general the best way to accomplish this
would be via static initialization with designated member initiators. 
Having some struct vm_unmapped_area_info instances not zero initialized
will put those sites at risk of feeding garbage into vm_unmapped_area() if
the convention is to zero initialize the struct and any new member
addition misses a call site that initializes each member manually.

It could be possible to leave the code mostly untouched, and just change
the line:
struct vm_unmapped_area_info info
to:
struct vm_unmapped_area_info info = {};

However, that would leave cleanup for the members that are manually set
to zero, as it would no longer be required.

So to be reduce the chance of bugs via uninitialized members, instead
simply continue the process to initialize the struct this way tree wide. 
This will zero any unspecified members.  Move the member initializers to
the struct declaration when they are known at that time.  Leave the
members out that were manually initialized to zero, as this would be
redundant for designated initializers.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lore.kernel.org/lkml/202402280912.33AEE7A9CF@keescook/#t
Link: https://lore.kernel.org/lkml/j7bfvig3gew3qruouxrh7z7ehjjafrgkbcmg6tcghhfh3rhmzi@wzlcoecgy5rs/
Signed-off-by: Rick Edgecombe <[email protected]>
Reviewed-by: Christophe Leroy <[email protected]>
Acked-by: Helge Deller <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Deepak Gupta <[email protected]>
Cc: Guo Ren <[email protected]>
Cc: H. Peter Anvin (Intel) <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Naveen N. Rao <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 98af719d5f85..f7722451276e 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -104,7 +104,9 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 	struct vm_area_struct *vma, *prev;
 	unsigned long filp_pgoff;
 	int do_color_align;
-	struct vm_unmapped_area_info info;
+	struct vm_unmapped_area_info info = {
+		.length = len
+	};
 
 	if (unlikely(len > TASK_SIZE))
 		return -ENOMEM;
@@ -139,7 +141,6 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 			return addr;
 	}
 
-	info.length = len;
 	info.align_mask = do_color_align ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
 	info.align_offset = shared_align_offset(filp_pgoff, pgoff);
 
@@ -160,7 +161,6 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 		 */
 	}
 
-	info.flags = 0;
 	info.low_limit = mm->mmap_base;
 	info.high_limit = mmap_upper_limit(NULL);
 	return vm_unmapped_area(&info);