4.17-stable review patch. If anyone has any objections, please let me know.
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From: Luis Henriques lhenriques@suse.com
[ Upstream commit 73fb0949cf246b212ff63d692a0ec88db954bb35 ]
KASAN found an UAF in ceph_statfs. This was a one-off bug but looking at the code it looks like the monmap access needs to be protected as it can be modified while we're accessing it. Fix this by protecting the access with the monc->mutex.
BUG: KASAN: use-after-free in ceph_statfs+0x21d/0x2c0 Read of size 8 at addr ffff88006844f2e0 by task trinity-c5/304
CPU: 0 PID: 304 Comm: trinity-c5 Not tainted 4.17.0-rc6+ #172 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 Call Trace: dump_stack+0xa5/0x11b ? show_regs_print_info+0x5/0x5 ? kmsg_dump_rewind+0x118/0x118 ? ceph_statfs+0x21d/0x2c0 print_address_description+0x73/0x2b0 ? ceph_statfs+0x21d/0x2c0 kasan_report+0x243/0x360 ceph_statfs+0x21d/0x2c0 ? ceph_umount_begin+0x80/0x80 ? kmem_cache_alloc+0xdf/0x1a0 statfs_by_dentry+0x79/0xb0 vfs_statfs+0x28/0x110 user_statfs+0x8c/0xe0 ? vfs_statfs+0x110/0x110 ? __fdget_raw+0x10/0x10 __se_sys_statfs+0x5d/0xa0 ? user_statfs+0xe0/0xe0 ? mutex_unlock+0x1d/0x40 ? __x64_sys_statfs+0x20/0x30 do_syscall_64+0xee/0x290 ? syscall_return_slowpath+0x1c0/0x1c0 ? page_fault+0x1e/0x30 ? syscall_return_slowpath+0x13c/0x1c0 ? prepare_exit_to_usermode+0xdb/0x140 ? syscall_trace_enter+0x330/0x330 ? __put_user_4+0x1c/0x30 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Allocated by task 130: __kmalloc+0x124/0x210 ceph_monmap_decode+0x1c1/0x400 dispatch+0x113/0xd20 ceph_con_workfn+0xa7e/0x44e0 process_one_work+0x5f0/0xa30 worker_thread+0x184/0xa70 kthread+0x1a0/0x1c0 ret_from_fork+0x35/0x40
Freed by task 130: kfree+0xb8/0x210 dispatch+0x15a/0xd20 ceph_con_workfn+0xa7e/0x44e0 process_one_work+0x5f0/0xa30 worker_thread+0x184/0xa70 kthread+0x1a0/0x1c0 ret_from_fork+0x35/0x40
Signed-off-by: Luis Henriques lhenriques@suse.com Reviewed-by: "Yan, Zheng" zyan@redhat.com Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ceph/super.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/fs/ceph/super.c +++ b/fs/ceph/super.c @@ -45,7 +45,7 @@ static void ceph_put_super(struct super_ static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf) { struct ceph_fs_client *fsc = ceph_inode_to_client(d_inode(dentry)); - struct ceph_monmap *monmap = fsc->client->monc.monmap; + struct ceph_mon_client *monc = &fsc->client->monc; struct ceph_statfs st; u64 fsid; int err; @@ -58,7 +58,7 @@ static int ceph_statfs(struct dentry *de }
dout("statfs\n"); - err = ceph_monc_do_statfs(&fsc->client->monc, data_pool, &st); + err = ceph_monc_do_statfs(monc, data_pool, &st); if (err < 0) return err;
@@ -94,8 +94,11 @@ static int ceph_statfs(struct dentry *de buf->f_namelen = NAME_MAX;
/* Must convert the fsid, for consistent values across arches */ - fsid = le64_to_cpu(*(__le64 *)(&monmap->fsid)) ^ - le64_to_cpu(*((__le64 *)&monmap->fsid + 1)); + mutex_lock(&monc->mutex); + fsid = le64_to_cpu(*(__le64 *)(&monc->monmap->fsid)) ^ + le64_to_cpu(*((__le64 *)&monc->monmap->fsid + 1)); + mutex_unlock(&monc->mutex); + buf->f_fsid.val[0] = fsid & 0xffffffff; buf->f_fsid.val[1] = fsid >> 32;