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authorTejun Heo <tj@kernel.org>2008-09-03 10:09:47 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-09-03 22:58:53 -0400
commitce36394269ccd9d1d286d6192ba09fa6894365e9 (patch)
treefb235ff6ea1363ae4fd933e29268e76cdade5682
parentd210baf53b699fc61aa891c177b71d7082d3b957 (diff)
mmap: fix petty bug in anonymous shared mmap offset handling
Anonymous mappings should ignore offset but shared anonymous mapping forgot to clear it and makes the following legit test program trigger SIGBUS. #include <sys/mman.h> #include <stdio.h> #include <errno.h> #define PAGE_SIZE 4096 int main(void) { char *p; int i; p = mmap(NULL, 2 * PAGE_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, PAGE_SIZE); if (p == MAP_FAILED) { perror("mmap"); return 1; } for (i = 0; i < 2; i++) { printf("page %d\n", i); p[i * 4096] = i; } return 0; } Fix it. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Hugh Dickins <hugh@veritas.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/mmap.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 339cf5c4d5d8..e7a5a68a9c2e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1030,6 +1030,10 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
1030 } else { 1030 } else {
1031 switch (flags & MAP_TYPE) { 1031 switch (flags & MAP_TYPE) {
1032 case MAP_SHARED: 1032 case MAP_SHARED:
1033 /*
1034 * Ignore pgoff.
1035 */
1036 pgoff = 0;
1033 vm_flags |= VM_SHARED | VM_MAYSHARE; 1037 vm_flags |= VM_SHARED | VM_MAYSHARE;
1034 break; 1038 break;
1035 case MAP_PRIVATE: 1039 case MAP_PRIVATE: