From: Sergei Trofimovich slyfox@gentoo.org
mainline inclusion from mainline-v5.13-rc1 commit f58bd538e6a2deb2bcdfe527d9ed45643348a4e6 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I49LY9 CVE: NA
-------------------------------------------------
When page_poison detects page corruption it's useful to see who freed a page recently to have a guess where write-after-free corruption happens.
After this change corruption report has extra page data. Example report from real corruption (includes only page_pwner part):
pagealloc: memory corruption e00000014cd61d10: 11 00 00 00 00 00 00 00 30 1d d2 ff ff 0f 00 60 ........0......` e00000014cd61d20: b0 1d d2 ff ff 0f 00 60 90 fe 1c 00 08 00 00 20 .......`....... ... CPU: 1 PID: 220402 Comm: cc1plus Not tainted 5.12.0-rc5-00107-g9720c6f59ecf #245 Hardware name: hp server rx3600, BIOS 04.03 04/08/2008 ... Call Trace: [<a000000100015210>] show_stack+0x90/0xc0 [<a000000101163390>] dump_stack+0x150/0x1c0 [<a0000001003f1e90>] __kernel_unpoison_pages+0x410/0x440 [<a0000001003c2460>] get_page_from_freelist+0x1460/0x2ca0 [<a0000001003c6be0>] __alloc_pages_nodemask+0x3c0/0x660 [<a0000001003ed690>] alloc_pages_vma+0xb0/0x500 [<a00000010037deb0>] __handle_mm_fault+0x1230/0x1fe0 [<a00000010037ef70>] handle_mm_fault+0x310/0x4e0 [<a00000010005dc70>] ia64_do_page_fault+0x1f0/0xb80 [<a00000010000ca00>] ia64_leave_kernel+0x0/0x270 page_owner tracks the page as freed page allocated via order 0, migratetype Movable, gfp_mask 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 37, ts 8173444098740 __reset_page_owner+0x40/0x200 free_pcp_prepare+0x4d0/0x600 free_unref_page+0x20/0x1c0 __put_page+0x110/0x1a0 migrate_pages+0x16d0/0x1dc0 compact_zone+0xfc0/0x1aa0 proactive_compact_node+0xd0/0x1e0 kcompactd+0x550/0x600 kthread+0x2c0/0x2e0 call_payload+0x50/0x80
Here we can see that page was freed by page migration but something managed to write to it afterwards.
[slyfox@gentoo.org: s/dump_page_owner/dump_page/, per Vlastimil] Link: https://lkml.kernel.org/r/20210407230800.1086854-1-slyfox@gentoo.org
Link: https://lkml.kernel.org/r/20210404141735.2152984-1-slyfox@gentoo.org Signed-off-by: Sergei Trofimovich slyfox@gentoo.org Acked-by: Vlastimil Babka vbabka@suse.cz Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org (cherry picked from commit f58bd538e6a2deb2bcdfe527d9ed45643348a4e6) Signed-off-by: Yuanzheng Song songyuanzheng@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- mm/page_poison.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/mm/page_poison.c b/mm/page_poison.c index a08423cb11ca..51f9cb913e0c 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -2,6 +2,7 @@ #include <linux/kernel.h> #include <linux/string.h> #include <linux/mm.h> +#include <linux/mmdebug.h> #include <linux/highmem.h> #include <linux/page_ext.h> #include <linux/poison.h> @@ -73,7 +74,7 @@ static bool single_bit_flip(unsigned char a, unsigned char b) return error && !(error & (error - 1)); }
-static void check_poison_mem(unsigned char *mem, size_t bytes) +static void check_poison_mem(struct page *page, unsigned char *mem, size_t bytes) { static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10); unsigned char *start; @@ -101,6 +102,7 @@ static void check_poison_mem(unsigned char *mem, size_t bytes) print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, end - start + 1, 1); dump_stack(); + dump_page(page, "pagealloc: corrupted page details"); }
static void unpoison_page(struct page *page) @@ -114,7 +116,7 @@ static void unpoison_page(struct page *page) * that is freed to buddy. Thus no extra check is done to * see if a page was poisoned. */ - check_poison_mem(kasan_reset_tag(addr), PAGE_SIZE); + check_poison_mem(page, kasan_reset_tag(addr), PAGE_SIZE); kasan_enable_current(); kunmap_atomic(addr); }