[PATCH 5.10 024/717] x86/mm/ident_map: Check for errors from ident_pud_init()

Greg Kroah-Hartman
2020-12-28T14:00:51Z

From: Arvind Sankar <nivedita@alum.mit.edu>

[ Upstream commit 1fcd009102ee02e217f2e7635ab65517d785da8e ]

Commit

ea3b5e60ce80 ("x86/mm/ident_map: Add 5-level paging support")

added ident_p4d_init() to support 5-level paging, but this function
doesn't check and return errors from ident_pud_init().

For example, the decompressor stub uses this code to create an identity
mapping. If it runs out of pages while trying to allocate a PMD
pagetable, the error will be currently ignored.

Fix this to propagate errors.

[ bp: Space out statements for better readability. ]

Fixes: ea3b5e60ce80 ("x86/mm/ident_map: Add 5-level paging support")
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20201027230648.1885111-1-nivedita@alum.mit.edu
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/mm/ident_map.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
index fe7a12599d8eb..968d7005f4a72 100644
--- a/arch/x86/mm/ident_map.c
+++ b/arch/x86/mm/ident_map.c
@@ -62,6 +62,7 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page,
unsigned long addr, unsigned long end)
{
unsigned long next;
+ int result;

for (; addr < end; addr = next) {
p4d_t *p4d = p4d_page + p4d_index(addr);
@@ -73,13 +74,20 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page,

if (p4d_present(*p4d)) {
pud = pud_offset(p4d, 0);
- ident_pud_init(info, pud, addr, next);
+ result = ident_pud_init(info, pud, addr, next);
+ if (result)
+ return result;
+
continue;
}
pud = (pud_t *)info->alloc_pgt_page(info->context);
if (!pud)
return -ENOMEM;
- ident_pud_init(info, pud, addr, next);
+
+ result = ident_pud_init(info, pud, addr, next);
+ if (result)
+ return result;
+
set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag));
}

--
2.27.0