The patch titled
Subject: fs: dcache: manually unpoison dname after allocation to shut up kasan's reports
has been added to the -mm tree. Its filename is
fs-dcache-manually-unpoison-dname-after-allocation-to-shut-up-kasans-reports.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-dcache-manually-unpoison-dname-after-allocation-to-shut-up-kasans-reports.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-dcache-manually-unpoison-dname-after-allocation-to-shut-up-kasans-reports.patch
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------------------------------------------------------
From: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Subject: fs: dcache: manually unpoison dname after allocation to shut up kasan's reports
We need to manually unpoison rounded up allocation size for dname to avoid
kasan's reports in dentry_string_cmp(). When CONFIG_DCACHE_WORD_ACCESS=y
dentry_string_cmp may access few bytes beyound requested in kmalloc()
size.
dentry_string_cmp() relates on that fact that dentry allocated using
kmalloc and kmalloc internally round up allocation size. So this is not a
bug, but this makes kasan to complain about such accesses. To avoid such
reports we mark rounded up allocation size in shadow as accessible.
Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Konstantin Serebryany <kcc@xxxxxxxxxx>
Cc: Dmitry Chernenkov <dmitryc@xxxxxxxxxx>
Cc: Andrey Konovalov <adech.fo@xxxxxxxxx>
Cc: Yuri Gribov <tetra2005@xxxxxxxxx>
Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dcache.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN fs/dcache.c~fs-dcache-manually-unpoison-dname-after-allocation-to-shut-up-kasans-reports fs/dcache.c
--- a/fs/dcache.c~fs-dcache-manually-unpoison-dname-after-allocation-to-shut-up-kasans-reports
+++ a/fs/dcache.c
@@ -38,6 +38,8 @@
#include <linux/prefetch.h>
#include <linux/ratelimit.h>
#include <linux/list_lru.h>
+#include <linux/kasan.h>
+
#include "internal.h"
#include "mount.h"
@@ -1430,6 +1432,9 @@ struct dentry *__d_alloc(struct super_bl
}
atomic_set(&p->u.count, 1);
dname = p->name;
+ if (IS_ENABLED(CONFIG_DCACHE_WORD_ACCESS))
+ kasan_unpoison_shadow(dname,
+ round_up(name->len + 1, sizeof(unsigned long)));
} else {
dname = dentry->d_iname;
}
_
Patches currently in -mm which might be from a.ryabinin@xxxxxxxxxxx are
compiler-introduce-__aliassymbol-shortcut.patch
add-kernel-address-sanitizer-infrastructure.patch
kasan-disable-memory-hotplug.patch
x86_64-add-kasan-support.patch
mm-page_alloc-add-kasan-hooks-on-alloc-and-free-paths.patch
mm-slub-introduce-virt_to_obj-function.patch
mm-slub-share-object_err-function.patch
mm-slub-introduce-metadata_access_enable-metadata_access_disable.patch
mm-slub-add-kernel-address-sanitizer-support-for-slub-allocator.patch
fs-dcache-manually-unpoison-dname-after-allocation-to-shut-up-kasans-reports.patch
kmemleak-disable-kasan-instrumentation-for-kmemleak.patch
lib-add-kasan-test-module.patch
x86_64-kasan-add-interceptors-for-memset-memmove-memcpy-functions.patch
kasan-enable-stack-instrumentation.patch
mm-vmalloc-add-flag-preventing-guard-hole-allocation.patch
mm-vmalloc-pass-additional-vm_flags-to-__vmalloc_node_range.patch
kernel-add-support-for-init_array-constructors.patch
module-fix-types-of-device-tables-aliases.patch
kasan-enable-instrumentation-of-global-variables.patch
hugetlb-sysctl-pass-extra1-=-null-rather-then-extra1-=-zero.patch
mm-hugetlb-fix-type-of-hugetlb_treat_as_movable-variable.patch
proc-pagemap-walk-page-tables-under-pte-lock.patch
linux-next.patch
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