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authorH. Peter Anvin <hpa@zytor.com>2010-02-18 19:13:40 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2010-02-21 11:57:08 -0500
commit87b8d1adefa1548b591cbf0d63965987e2cf893d (patch)
tree9bb71e42dfed2ac212a9dc55dd5e2ba1f8d042ac /mm
parentaea187c46f7d03ce985e55eb1398d0776a15b928 (diff)
mm: Make copy_from_user() in migrate.c statically predictable
x86-32 has had a static test for copy_on_user() overflow for a while. This test currently fails in mm/migrate.c resulting in an allyesconfig/allmodconfig build failure on x86-32: In function ‘copy_from_user’, inlined from ‘do_pages_stat’ at /home/hpa/kernel/git/mm/migrate.c:1012: /home/hpa/kernel/git/arch/x86/include/asm/uaccess_32.h:212: error: call to ‘copy_from_user_overflow’ declared Make the logic more explicit and therefore easier for gcc to understand. v2: rewrite the loop entirely using a more normal structure for a chunked-data loop (Linus Torvalds) Reported-by: Len Brown <lenb@kernel.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Reviewed-and-Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Arjan van de Ven <arjan@linux.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/migrate.c36
1 files changed, 15 insertions, 21 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 9a0db5bbabe4..880bd592d38e 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1002,33 +1002,27 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
1002#define DO_PAGES_STAT_CHUNK_NR 16 1002#define DO_PAGES_STAT_CHUNK_NR 16
1003 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; 1003 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
1004 int chunk_status[DO_PAGES_STAT_CHUNK_NR]; 1004 int chunk_status[DO_PAGES_STAT_CHUNK_NR];
1005 unsigned long i, chunk_nr = DO_PAGES_STAT_CHUNK_NR;
1006 int err;
1007 1005
1008 for (i = 0; i < nr_pages; i += chunk_nr) { 1006 while (nr_pages) {
1009 if (chunk_nr > nr_pages - i) 1007 unsigned long chunk_nr;
1010 chunk_nr = nr_pages - i;
1011 1008
1012 err = copy_from_user(chunk_pages, &pages[i], 1009 chunk_nr = nr_pages;
1013 chunk_nr * sizeof(*chunk_pages)); 1010 if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
1014 if (err) { 1011 chunk_nr = DO_PAGES_STAT_CHUNK_NR;
1015 err = -EFAULT; 1012
1016 goto out; 1013 if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages)))
1017 } 1014 break;
1018 1015
1019 do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); 1016 do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
1020 1017
1021 err = copy_to_user(&status[i], chunk_status, 1018 if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
1022 chunk_nr * sizeof(*chunk_status)); 1019 break;
1023 if (err) {
1024 err = -EFAULT;
1025 goto out;
1026 }
1027 }
1028 err = 0;
1029 1020
1030out: 1021 pages += chunk_nr;
1031 return err; 1022 status += chunk_nr;
1023 nr_pages -= chunk_nr;
1024 }
1025 return nr_pages ? -EFAULT : 0;
1032} 1026}
1033 1027
1034/* 1028/*