The patch titled
Subject: highmem: fix kmap_to_page() for kmap_local_page() addresses
has been added to the -mm mm-unstable branch. Its filename is
highmem-fix-kmap_to_page-for-kmap_local_page-addresses.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/highmem-fix-kmap_to_page-for-kmap_local_page-addresses.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Ira Weiny <ira.weiny@xxxxxxxxx>
Subject: highmem: fix kmap_to_page() for kmap_local_page() addresses
Date: Wed, 5 Oct 2022 21:05:55 -0700
kmap_to_page() is used to get the page for a virtual address which may
be kmap'ed. Unfortunately, kmap_local_page() stores mappings in a
thread local array separate from kmap(). These mappings were not
checked by the call.
Check the kmap_local_page() mappings and return the page if found.
Because it is intended to remove kmap_to_page() add a warn on once to
the kmap checks to flag potential issues early.
NOTE Due to 32bit x86 use of kmap local in iomap atmoic, KMAP_LOCAL does
not require HIGHMEM to be set. Therefore the support calls required a
new KMAP_LOCAL section to fix 0day build errors.
Link: https://lkml.kernel.org/r/20221006040555.1502679-1-ira.weiny@xxxxxxxxx
Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Cc: "Fabio M. De Francesco" <fmdefrancesco@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/highmem.c | 42 ++++++++++++++++++++++++++++++++----------
1 file changed, 32 insertions(+), 10 deletions(-)
--- a/mm/highmem.c~highmem-fix-kmap_to_page-for-kmap_local_page-addresses
+++ a/mm/highmem.c
@@ -30,6 +30,17 @@
#include <asm/tlbflush.h>
#include <linux/vmalloc.h>
+#ifdef CONFIG_KMAP_LOCAL
+static inline int kmap_local_calc_idx(int idx)
+{
+ return idx + KM_MAX_IDX * smp_processor_id();
+}
+
+#ifndef arch_kmap_local_map_idx
+#define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx)
+#endif
+#endif /* CONFIG_KMAP_LOCAL */
+
/*
* Virtual_count is not a pure "count".
* 0 means that it is not mapped, and has not been mapped
@@ -142,14 +153,34 @@ pte_t *pkmap_page_table;
struct page *__kmap_to_page(void *vaddr)
{
+ unsigned long base = (unsigned long) vaddr & PAGE_MASK;
+ struct kmap_ctrl *kctrl = ¤t->kmap_ctrl;
unsigned long addr = (unsigned long)vaddr;
+ int i;
- if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
+ /* kmap() mappings */
+ if (WARN_ON_ONCE(addr >= PKMAP_ADDR(0) &&
+ addr < PKMAP_ADDR(LAST_PKMAP))) {
int i = PKMAP_NR(addr);
return pte_page(pkmap_page_table[i]);
}
+ /* kmap_local_page() mappings */
+ if (WARN_ON_ONCE(base >= __fix_to_virt(FIX_KMAP_END) &&
+ base < __fix_to_virt(FIX_KMAP_BEGIN))) {
+ for (i = 0; i < kctrl->idx; i++) {
+ unsigned long base_addr;
+ int idx;
+
+ idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));
+ base_addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+
+ if (base_addr == base)
+ return pte_page(kctrl->pteval[i]);
+ }
+ }
+
return virt_to_page(vaddr);
}
EXPORT_SYMBOL(__kmap_to_page);
@@ -462,10 +493,6 @@ static inline void kmap_local_idx_pop(vo
# define arch_kmap_local_post_unmap(vaddr) do { } while (0)
#endif
-#ifndef arch_kmap_local_map_idx
-#define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx)
-#endif
-
#ifndef arch_kmap_local_unmap_idx
#define arch_kmap_local_unmap_idx(idx, vaddr) kmap_local_calc_idx(idx)
#endif
@@ -494,11 +521,6 @@ static inline bool kmap_high_unmap_local
return false;
}
-static inline int kmap_local_calc_idx(int idx)
-{
- return idx + KM_MAX_IDX * smp_processor_id();
-}
-
static pte_t *__kmap_pte;
static pte_t *kmap_get_pte(unsigned long vaddr, int idx)
_
Patches currently in -mm which might be from ira.weiny@xxxxxxxxx are
highmem-fix-kmap_to_page-for-kmap_local_page-addresses.patch
