Patch "selftests/vm: fix map_hugetlb length used for testing read and write" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests/vm: fix map_hugetlb length used for testing read and write

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-vm-fix-map_hugetlb-length-used-for-testing.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fbe0827af2aa1e840b048d5c85c51af790082f8d
Author: Christophe Leroy <christophe.leroy@xxxxxx>
Date:   Wed Apr 1 21:11:51 2020 -0700

    selftests/vm: fix map_hugetlb length used for testing read and write
    
    [ Upstream commit cabc30da10e677c67ab9a136b1478175734715c5 ]
    
    Commit fa7b9a805c79 ("tools/selftest/vm: allow choosing mem size and page
    size in map_hugetlb") added the possibility to change the size of memory
    mapped for the test, but left the read and write test using the default
    value.  This is unnoticed when mapping a length greater than the default
    one, but segfaults otherwise.
    
    Fix read_bytes() and write_bytes() by giving them the real length.
    
    Also fix the call to munmap().
    
    Fixes: fa7b9a805c79 ("tools/selftest/vm: allow choosing mem size and page size in map_hugetlb")
    Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
    Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Leonardo Bras <leonardo@xxxxxxxxxxxxx>
    Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
    Cc: Shuah Khan <shuah@xxxxxxxxxx>
    Cc: <stable@xxxxxxxxxxxxxxx>
    Link: http://lkml.kernel.org/r/9a404a13c871c4bd0ba9ede68f69a1225180dd7e.1580978385.git.christophe.leroy@xxxxxx
    Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/vm/map_hugetlb.c b/tools/testing/selftests/vm/map_hugetlb.c
index 7b41cc6ecb0bf..c65c55b7a789f 100644
--- a/tools/testing/selftests/vm/map_hugetlb.c
+++ b/tools/testing/selftests/vm/map_hugetlb.c
@@ -46,20 +46,20 @@ static void check_bytes(char *addr)
 	printf("First hex is %x\n", *((unsigned int *)addr));
 }
 
-static void write_bytes(char *addr)
+static void write_bytes(char *addr, size_t length)
 {
 	unsigned long i;
 
-	for (i = 0; i < LENGTH; i++)
+	for (i = 0; i < length; i++)
 		*(addr + i) = (char)i;
 }
 
-static int read_bytes(char *addr)
+static int read_bytes(char *addr, size_t length)
 {
 	unsigned long i;
 
 	check_bytes(addr);
-	for (i = 0; i < LENGTH; i++)
+	for (i = 0; i < length; i++)
 		if (*(addr + i) != (char)i) {
 			printf("Mismatch at %lu\n", i);
 			return 1;
@@ -103,11 +103,11 @@ int main(int argc, char **argv)
 
 	printf("Returned address is %p\n", addr);
 	check_bytes(addr);
-	write_bytes(addr);
-	ret = read_bytes(addr);
+	write_bytes(addr, length);
+	ret = read_bytes(addr, length);
 
 	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
-	if (munmap(addr, LENGTH)) {
+	if (munmap(addr, length)) {
 		perror("munmap");
 		exit(1);
 	}