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9d78edeaec
syzbot found that touch /proc/testfile causes NULL pointer dereference at tomoyo_get_local_path() because inode of the dentry is NULL. Beforec59f415a7c, Tomoyo received pid_ns from proc's s_fs_info directly. Since proc_pid_ns() can only work with inode, using it in the tomoyo_get_local_path() was wrong. To avoid creating more functions for getting proc_ns, change the argument type of the proc_pid_ns() function. Then, Tomoyo can use the existing super_block to get pid_ns. Link: https://lkml.kernel.org/r/0000000000002f0c7505a5b0e04c@google.com Link: https://lkml.kernel.org/r/20200518180738.2939611-1-gladkov.alexey@gmail.com Reported-by: syzbot+c1af344512918c61362c@syzkaller.appspotmail.com Fixes:c59f415a7c("Use proc_pid_ns() to get pid_namespace from the proc superblock") Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
74 lines
1.7 KiB
C
74 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/cache.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/pid_namespace.h>
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#include "internal.h"
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/*
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* /proc/self:
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*/
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static const char *proc_self_get_link(struct dentry *dentry,
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struct inode *inode,
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struct delayed_call *done)
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{
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struct pid_namespace *ns = proc_pid_ns(inode->i_sb);
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pid_t tgid = task_tgid_nr_ns(current, ns);
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char *name;
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if (!tgid)
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return ERR_PTR(-ENOENT);
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/* max length of unsigned int in decimal + NULL term */
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name = kmalloc(10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);
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if (unlikely(!name))
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return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
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sprintf(name, "%u", tgid);
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set_delayed_call(done, kfree_link, name);
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return name;
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}
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static const struct inode_operations proc_self_inode_operations = {
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.get_link = proc_self_get_link,
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};
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static unsigned self_inum __ro_after_init;
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int proc_setup_self(struct super_block *s)
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{
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struct inode *root_inode = d_inode(s->s_root);
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struct proc_fs_info *fs_info = proc_sb_info(s);
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struct dentry *self;
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int ret = -ENOMEM;
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inode_lock(root_inode);
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self = d_alloc_name(s->s_root, "self");
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if (self) {
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struct inode *inode = new_inode_pseudo(s);
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if (inode) {
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inode->i_ino = self_inum;
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inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
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inode->i_mode = S_IFLNK | S_IRWXUGO;
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inode->i_uid = GLOBAL_ROOT_UID;
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inode->i_gid = GLOBAL_ROOT_GID;
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inode->i_op = &proc_self_inode_operations;
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d_add(self, inode);
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ret = 0;
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} else {
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dput(self);
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}
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}
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inode_unlock(root_inode);
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if (ret)
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pr_err("proc_fill_super: can't allocate /proc/self\n");
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else
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fs_info->proc_self = self;
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return ret;
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}
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void __init proc_self_init(void)
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{
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proc_alloc_inum(&self_inum);
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}
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