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maccess: always use strict semantics for probe_kernel_read

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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 <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200521152301.2587579-17-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Hellwig
2020-06-08 21:34:50 -07:00
committed by Linus Torvalds
parent 7676fbf21b
commit 98a23609b1
8 changed files with 19 additions and 54 deletions
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10
mm/debug.c
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@@ -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);