5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chao Yu <yuch...@huawei.com>

commit 8bce6dcede65139a087ff240127e3f3c01363eed upstream.

erofs_vmap() wrapped vmap() and vm_map_ram() to return virtual
continuous memory, but both of them can failed due to a lot of
reason, previously, erofs_vmap()'s callers didn't handle them,
which can potentially cause NULL pointer access, fix it.

Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support")
Fixes: 0d40d6e399c1 ("staging: erofs: add a generic z_erofs VLE decompressor")
Cc: <sta...@vger.kernel.org> # 4.19+
Signed-off-by: Gao Xiang <gaoxian...@huawei.com>
Signed-off-by: Chao Yu <yuch...@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/staging/erofs/unzip_vle.c     |    4 ++++
 drivers/staging/erofs/unzip_vle_lz4.c |    7 +++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/staging/erofs/unzip_vle.c
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -1034,6 +1034,10 @@ repeat:
 
 skip_allocpage:
        vout = erofs_vmap(pages, nr_pages);
+       if (!vout) {
+               err = -ENOMEM;
+               goto out;
+       }
 
        err = z_erofs_vle_unzip_vmap(compressed_pages,
                clusterpages, vout, llen, work->pageofs, overlapped);
--- a/drivers/staging/erofs/unzip_vle_lz4.c
+++ b/drivers/staging/erofs/unzip_vle_lz4.c
@@ -136,10 +136,13 @@ int z_erofs_vle_unzip_fast_percpu(struct
 
        nr_pages = DIV_ROUND_UP(outlen + pageofs, PAGE_SIZE);
 
-       if (clusterpages == 1)
+       if (clusterpages == 1) {
                vin = kmap_atomic(compressed_pages[0]);
-       else
+       } else {
                vin = erofs_vmap(compressed_pages, clusterpages);
+               if (!vin)
+                       return -ENOMEM;
+       }
 
        preempt_disable();
        vout = erofs_pcpubuf[smp_processor_id()].data;


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