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authorKalesh Singh <kaleshsingh@google.com>2020-12-29 15:14:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-29 15:36:49 -0800
commite05986ee7a5814bec0e0075d813daca3d46e4a9e (patch)
tree49d3a5bbfa9d636584d8e449c349cd0d75663bff
parentdc2da7b45ffe954a0090f5d0310ed7b0b37d2bd2 (diff)
downloadlinux-stericsson-e05986ee7a5814bec0e0075d813daca3d46e4a9e.tar.gz
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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/mremap.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/mremap.c b/mm/mremap.c
index c5590afe7165..f554320281cc 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -358,7 +358,9 @@ static unsigned long get_extent(enum pgt_entry entry, unsigned long old_addr,
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;