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([171.76.83.153]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2152d2cf14esm34830485ad.207.2024.11.29.23.02.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Nov 2024 23:02:13 -0800 (PST) From: Nihar Chaithanya To: miklos@szeredi.hu Cc: joannelkoong@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, Nihar Chaithanya , syzbot+87b8e6ed25dbc41759f7@syzkaller.appspotmail.com Subject: [PATCH] fuse: add a null-ptr check Date: Sat, 30 Nov 2024 12:21:22 +0530 Message-Id: <20241130065118.539620-1-niharchaithanya@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The bug KASAN: null-ptr-deref is triggered due to *val being dereferenced when it is null in fuse_copy_do() when performing memcpy(). Add a check in fuse_copy_one() to prevent this. Reported-by: syzbot+87b8e6ed25dbc41759f7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D87b8e6ed25dbc41759f7 Fixes: 3b97c3652d91 ("fuse: convert direct io to use folios") Tested-by: syzbot+87b8e6ed25dbc41759f7@syzkaller.appspotmail.com Signed-off-by: Nihar Chaithanya --- fs/fuse/dev.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 563a0bfa0e95..9c93759ac14b 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1070,6 +1070,9 @@ static int fuse_copy_pages(struct fuse_copy_state *cs= , unsigned nbytes, /* Copy a single argument in the request to/from userspace buffer */ static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned s= ize) { + if (!val) + return -EINVAL; + while (size) { if (!cs->len) { int err =3D fuse_copy_fill(cs); --=20 2.34.1