From 803a6f1b3326b05ac4a3761e3abaecef37c2e2f4 Mon Sep 17 00:00:00 2001
From: Pavel Skripkin <paskripkin@gmail.com>
Date: Wed, 11 Aug 2021 20:50:52 +0300
Subject: udmabuf: fix general protection fault in udmabuf_create
Git-commit: b9770b0b6eac2be3772b6f4748e6b899a9ab2870
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
Syzbot reported general protection fault in udmabuf_create. The problem
was in wrong error handling.
In commit 16c243e99d33 ("udmabuf: Add support for mapping hugepages (v4)")
shmem_read_mapping_page() call was replaced with find_get_page_flags(),
but find_get_page_flags() returns NULL on failure instead PTR_ERR().
Wrong error checking was causing GPF in get_page(), since passed page
was equal to NULL. Fix it by changing if (IS_ER(!hpage)) to if (!hpage)
Reported-by: syzbot+e9cd3122a37c5d6c51e8@syzkaller.appspotmail.com
Fixes: 16c243e99d33 ("udmabuf: Add support for mapping hugepages (v4)")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20210811175052.21254-1-paskripkin@gmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/dma-buf/udmabuf.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 8df761a10251..c57a609db75b 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -227,8 +227,8 @@ static long udmabuf_create(struct miscdevice *device,
if (!hpage) {
hpage = find_get_page_flags(mapping, pgoff,
FGP_ACCESSED);
- if (IS_ERR(hpage)) {
- ret = PTR_ERR(hpage);
+ if (!hpage) {
+ ret = -EINVAL;
goto err;
}
}
--
2.38.1