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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, deller@gmx.de, kaleshsingh@google.com,
	kirill.shutemov@linux.intel.com, linux-mm@kvack.org,
	linux@roeck-us.net, lokeshgidra@google.com, minchan@kernel.org,
	mm-commits@vger.kernel.org, surenb@google.com,
	torvalds@linux-foundation.org
Subject: [patch 07/16] mm/mremap.c: fix extent calculation
Date: Tue, 29 Dec 2020 15:14:40 -0800	[thread overview]
Message-ID: <20201229231440.q8f_qyKwg%akpm@linux-foundation.org> (raw)
In-Reply-To: <20201229151349.3285926ec0d1f65a27ac8534@linux-foundation.org>

From: Kalesh Singh <kaleshsingh@google.com>
Subject: mm/mremap.c: fix extent calculation

When `next < old_addr`, `next - old_addr` arithmetic underflows
causing `extent` to be incorrect.

Make `extent` the smaller of `next - old_addr` or `old_end - old_addr`.

Link: https://lkml.kernel.org/r/20201219170433.2418867-1-kaleshsingh@google.com
Fixes: c49dd34018026 ("mm: speedup mremap on 1GB or larger regions")
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mremap.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/mremap.c~mm-mremap-fix-extent-calculation
+++ a/mm/mremap.c
@@ -358,7 +358,9 @@ static unsigned long get_extent(enum pgt
 
 	next = (old_addr + size) & mask;
 	/* even if next overflowed, extent below will be ok */
-	extent = (next > old_end) ? old_end - old_addr : next - old_addr;
+	extent = next - old_addr;
+	if (extent > old_end - old_addr)
+		extent = old_end - old_addr;
 	next = (new_addr + size) & mask;
 	if (extent > next - new_addr)
 		extent = next - new_addr;
_


  parent reply	other threads:[~2020-12-29 23:14 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-29 23:13 incoming Andrew Morton
2020-12-29 23:14 ` [patch 01/16] selftests/vm: fix building protection keys test Andrew Morton
2020-12-29 23:14 ` [patch 02/16] mm/hugetlb: fix deadlock in hugetlb_cow error path Andrew Morton
2020-12-29 23:14 ` [patch 03/16] Revert "kbuild: avoid static_assert for genksyms" Andrew Morton
2020-12-29 23:14 ` [patch 04/16] checkpatch: prefer strscpy to strlcpy Andrew Morton
2020-12-29 23:14 ` [patch 05/16] mm: add prototype for __add_to_page_cache_locked() Andrew Morton
2020-12-29 23:14 ` [patch 06/16] mm: memmap defer init doesn't work as expected Andrew Morton
2020-12-29 23:14 ` Andrew Morton [this message]
2020-12-29 23:14 ` [patch 08/16] mm: generalise COW SMC TLB flushing race comment Andrew Morton
2020-12-29 23:14 ` [patch 09/16] kasan: fix null pointer dereference in kasan_record_aux_stack Andrew Morton
2020-12-29 23:14 ` [patch 10/16] local64.h: make <asm/local64.h> mandatory Andrew Morton
2020-12-29 23:14 ` [patch 11/16] sizes.h: add SZ_8G/SZ_16G/SZ_32G macros Andrew Morton
2020-12-29 23:14 ` [patch 12/16] kdev_t: always inline major/minor helper functions Andrew Morton
2020-12-29 23:14 ` [patch 13/16] lib/genalloc: fix the overflow when size is too big Andrew Morton
2020-12-29 23:15 ` [patch 14/16] lib/zlib: fix inflating zlib streams on s390 Andrew Morton
2020-12-29 23:15 ` [patch 15/16] zlib: move EXPORT_SYMBOL() and MODULE_LICENSE() out of dfltcc_syms.c Andrew Morton
2020-12-29 23:15 ` [patch 16/16] mm: slub: call account_slab_page() after slab page initialization Andrew Morton

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