Unverified Commit 7c022500 authored by Yuto Ohnuki's avatar Yuto Ohnuki Committed by Christian Brauner
Browse files

fs: improve dump_inode() to safely access inode fields 



Use get_kernel_nofault() to safely access inode and related structures
(superblock, file_system_type) to avoid crashing when the inode pointer
is invalid. This allows the same pattern as dump_mapping().

Note: The original access method for i_state and i_count is preserved,
as get_kernel_nofault() is unnecessary once the inode structure is
verified accessible.

Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarYuto Ohnuki <ytohnuki@amazon.com>
Link: https://patch.msgid.link/20260112181443.81286-1-ytohnuki@amazon.com


Reviewed-by: default avatarMateusz Guzik <mjguzik@gmail.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 58ecde96

fs/inode.c

+34 −13
Original line number Diff line number Diff line
@@ -2984,24 +2984,45 @@ umode_t mode_strip_sgid(struct mnt_idmap *idmap, 
EXPORT_SYMBOL(mode_strip_sgid);



#ifdef CONFIG_DEBUG_VFS

/*

 * Dump an inode.

 *

 * TODO: add a proper inode dumping routine, this is a stub to get debug off the

 * ground.

/**

 * dump_inode - dump an inode.

 * @inode: inode to dump

 * @reason: reason for dumping

 *

 * TODO: handle getting to fs type with get_kernel_nofault()?

 * See dump_mapping() above.

 * If inode is an invalid pointer, we don't want to crash accessing it,

 * so probe everything depending on it carefully with get_kernel_nofault().

 */

void dump_inode(struct inode *inode, const char *reason)

{

	struct super_block *sb = inode->i_sb;



	pr_warn("%s encountered for inode %px\n"

		"fs %s mode %ho opflags 0x%hx flags 0x%x state 0x%x count %d\n",

		reason, inode, sb->s_type->name, inode->i_mode, inode->i_opflags,

		inode->i_flags, inode_state_read_once(inode), atomic_read(&inode->i_count));

	struct super_block *sb;

	struct file_system_type *s_type;

	const char *fs_name_ptr;

	char fs_name[32] = {};

	umode_t mode;

	unsigned short opflags;

	unsigned int flags;

	unsigned int state;

	int count;



	if (get_kernel_nofault(sb, &inode->i_sb) ||

	    get_kernel_nofault(mode, &inode->i_mode) ||

	    get_kernel_nofault(opflags, &inode->i_opflags) ||

	    get_kernel_nofault(flags, &inode->i_flags)) {

		pr_warn("%s: unreadable inode:%px\n", reason, inode);

		return;

	}



	state = inode_state_read_once(inode);

	count = atomic_read(&inode->i_count);



	if (!sb ||

	    get_kernel_nofault(s_type, &sb->s_type) || !s_type ||

	    get_kernel_nofault(fs_name_ptr, &s_type->name) || !fs_name_ptr ||

	    strncpy_from_kernel_nofault(fs_name, fs_name_ptr, sizeof(fs_name) - 1) < 0)

		strscpy(fs_name, "<unknown, sb unreadable>");



	pr_warn("%s: inode:%px fs:%s mode:%ho opflags:%#x flags:%#x state:%#x count:%d\n",

		reason, inode, fs_name, mode, opflags, flags, state, count);

}

EXPORT_SYMBOL(dump_inode);

#endif