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proc/kcore: do not try to access unaccepted memory

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Support for unaccepted memory was added recently, refer commit
dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby a virtual
machine may need to accept memory before it can be used.

Do not try to access unaccepted memory because it can cause the guest to
fail.

For /proc/kcore, which is read-only and does not support mmap, this means a
read of unaccepted memory will return zeros.

Link: https://lkml.kernel.org/r/20230911112114.91323-3-adrian.hunter@intel.com
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Adrian Hunter 2023-09-11 14:21:14 +03:00 committed by Andrew Morton
parent 7cd34dd3c9
commit e538a58209
1 changed files with 2 additions and 1 deletions
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3
fs/proc/kcore.c
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@ -546,7 +546,8 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter)
* and explicitly excluded physical ranges.
*/
if (!page || PageOffline(page) ||
is_page_hwpoison(page) || !pfn_is_ram(pfn)) {
is_page_hwpoison(page) || !pfn_is_ram(pfn) ||
pfn_is_unaccepted_memory(pfn)) {
if (iov_iter_zero(tsz, iter) != tsz) {
ret = -EFAULT;
goto out;