@@ -3392,7 +3392,7 @@ static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
break;
case Opt_nr_blocks:
ctx->blocks = memparse(param->string, &rest);
- if (*rest)
+ if (*rest || ctx->blocks > S64_MAX)
goto bad_value;
ctx->seen |= SHMEM_SEEN_BLOCKS;
break;
@@ -3514,10 +3514,7 @@ static int shmem_reconfigure(struct fs_context *fc)
raw_spin_lock(&sbinfo->stat_lock);
inodes = sbinfo->max_inodes - sbinfo->free_inodes;
- if (ctx->blocks > S64_MAX) {
- err = "Number of blocks too large";
- goto out;
- }
+
if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
if (!sbinfo->max_blocks) {
err = "Cannot retroactively limit size";
An undefined-behavior issue has not been completely fixed since commit d14f5efadd84 ("tmpfs: fix undefined-behaviour in shmem_reconfigure()"). In the commit, check in the shmem_reconfigure() is added in remount process to avoid the Ubsan problem. However, the check is not added to the mount process.It cause the inconsistent results between mount and remount. The operations to reproduce the problem in user mode as follow: If nr_blocks is set to 0x8000000000000000, the mounting is successful. # mount tmpfs /dev/shm/ -t tmpfs -o nr_blocks=0x8000000000000000 However, when -o remount is used, the mount fails because of the check in the shmem_reconfigure() # mount tmpfs /dev/shm/ -t tmpfs -o remount,nr_blocks=0x8000000000000000 mount: /dev/shm: mount point not mounted or bad option. Therefore, add checks in the shmem_parse_one() function and remove the check in shmem_reconfigure() to avoid this problem. Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com> --- mm/shmem.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)