From 98a23609b10364a51a1bb3688f8dd1cd1aa94a9a Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 8 Jun 2020 21:34:50 -0700 Subject: maccess: always use strict semantics for probe_kernel_read Except for historical confusion in the kprobes/uprobes and bpf tracers, which has been fixed now, there is no good reason to ever allow user memory accesses from probe_kernel_read. Switch probe_kernel_read to only read from kernel memory. [akpm@linux-foundation.org: update it for "mm, dump_page(): do not crash with invalid mapping pointer"] Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20200521152301.2587579-17-hch@lst.de Signed-off-by: Linus Torvalds --- mm/debug.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'mm/debug.c') diff --git a/mm/debug.c b/mm/debug.c index f2ede2df585a..b5b1de8c71ac 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -120,9 +120,9 @@ void __dump_page(struct page *page, const char *reason) * mapping can be invalid pointer and we don't want to crash * accessing it, so probe everything depending on it carefully */ - if (probe_kernel_read_strict(&host, &mapping->host, - sizeof(struct inode *)) || - probe_kernel_read_strict(&a_ops, &mapping->a_ops, + if (probe_kernel_read(&host, &mapping->host, + sizeof(struct inode *)) || + probe_kernel_read(&a_ops, &mapping->a_ops, sizeof(struct address_space_operations *))) { pr_warn("failed to read mapping->host or a_ops, mapping not a valid kernel address?\n"); goto out_mapping; @@ -133,7 +133,7 @@ void __dump_page(struct page *page, const char *reason) goto out_mapping; } - if (probe_kernel_read_strict(&dentry_first, + if (probe_kernel_read(&dentry_first, &host->i_dentry.first, sizeof(struct hlist_node *))) { pr_warn("mapping->a_ops:%ps with invalid mapping->host inode address %px\n", a_ops, host); @@ -146,7 +146,7 @@ void __dump_page(struct page *page, const char *reason) } dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias); - if (probe_kernel_read_strict(&dentry, dentry_ptr, + if (probe_kernel_read(&dentry, dentry_ptr, sizeof(struct dentry))) { pr_warn("mapping->aops:%ps with invalid mapping->host->i_dentry.first %px\n", a_ops, dentry_ptr); -- cgit v1.2.3-70-g09d2