The patch titled
Subject: alloc_tag: fix module allocation tags populated area calculation
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
alloc_tag-fix-module-allocation-tags-populated-area-calculation.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/alloc_tag-fix-module-allocation-tags-populated-area-calculation.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: alloc_tag: fix module allocation tags populated area calculation
Date: Fri, 29 Nov 2024 16:14:22 -0800
vm_module_tags_populate() calculation of the populated area assumes that
area starts at a page boundary and therefore when new pages are allocation,
the end of the area is page-aligned as well. If the start of the area is
not page-aligned then allocating a page and incrementing the end of the
area by PAGE_SIZE leads to an area at the end but within the area boundary
which is not populated. Accessing this are will lead to a kernel panic.
Fix the calculation by down-aligning the start of the area and using that
as the location allocated pages are mapped to.
Link: https://lkml.kernel.org/r/20241130001423.1114965-1-surenb@xxxxxxxxxx
Fixes: 0f9b685626da ("alloc_tag: populate memory for module tags as needed")
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202411132111.6a221562-lkp@xxxxxxxxx
Cc: David Wang <00107082@xxxxxxx>
Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Cc: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
Cc: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Sourav Panda <souravpanda@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/alloc_tag.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/lib/alloc_tag.c~alloc_tag-fix-module-allocation-tags-populated-area-calculation
+++ a/lib/alloc_tag.c
@@ -401,19 +401,20 @@ repeat:
static int vm_module_tags_populate(void)
{
- unsigned long phys_size = vm_module_tags->nr_pages << PAGE_SHIFT;
+ unsigned long phys_end = ALIGN_DOWN(module_tags.start_addr, PAGE_SIZE) +
+ (vm_module_tags->nr_pages << PAGE_SHIFT);
+ unsigned long new_end = module_tags.start_addr + module_tags.size;
- if (phys_size < module_tags.size) {
+ if (phys_end < new_end) {
struct page **next_page = vm_module_tags->pages + vm_module_tags->nr_pages;
- unsigned long addr = module_tags.start_addr + phys_size;
unsigned long more_pages;
unsigned long nr;
- more_pages = ALIGN(module_tags.size - phys_size, PAGE_SIZE) >> PAGE_SHIFT;
+ more_pages = ALIGN(new_end - phys_end, PAGE_SIZE) >> PAGE_SHIFT;
nr = alloc_pages_bulk_array_node(GFP_KERNEL | __GFP_NOWARN,
NUMA_NO_NODE, more_pages, next_page);
if (nr < more_pages ||
- vmap_pages_range(addr, addr + (nr << PAGE_SHIFT), PAGE_KERNEL,
+ vmap_pages_range(phys_end, phys_end + (nr << PAGE_SHIFT), PAGE_KERNEL,
next_page, PAGE_SHIFT) < 0) {
/* Clean up and error out */
for (int i = 0; i < nr; i++)
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
alloc_tag-fix-module-allocation-tags-populated-area-calculation.patch
alloc_tag-fix-set_codetag_empty-when-config_mem_alloc_profiling_debug.patch
mm-convert-mm_lock_seq-to-a-proper-seqcount.patch
mm-introduce-mmap_lock_speculation_beginend.patch
