The patch titled
Subject: mm/debug.c: do not dereference i_ino blindly
has been added to the -mm tree. Its filename is
mm-debug-do-not-dereference-i_ino-blindly.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-debug-do-not-dereference-i_ino-blindly.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-debug-do-not-dereference-i_ino-blindly.patch
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm/debug.c: do not dereference i_ino blindly
__dump_page() checks i_dentry is fetchable and i_ino is earlier in the
struct than i_ino, so it ought to work fine, but it's possible that struct
randomisation has reordered i_ino after i_dentry and the pointer is just
wild enough that i_dentry is fetchable and i_ino isn't.
Also print the inode number if the dentry is invalid.
Link: https://lkml.kernel.org/r/20200819185710.28180-1-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reported-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/debug.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/mm/debug.c~mm-debug-do-not-dereference-i_ino-blindly
+++ a/mm/debug.c
@@ -120,6 +120,7 @@ void __dump_page(struct page *page, cons
struct hlist_node *dentry_first;
struct dentry *dentry_ptr;
struct dentry dentry;
+ unsigned long ino;
/*
* mapping can be invalid pointer and we don't want to crash
@@ -136,21 +137,22 @@ void __dump_page(struct page *page, cons
goto out_mapping;
}
- if (get_kernel_nofault(dentry_first, &host->i_dentry.first)) {
+ if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
+ get_kernel_nofault(ino, &host->i_ino)) {
pr_warn("aops:%ps with invalid host inode %px\n",
a_ops, host);
goto out_mapping;
}
if (!dentry_first) {
- pr_warn("aops:%ps ino:%lx\n", a_ops, host->i_ino);
+ pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
goto out_mapping;
}
dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
if (get_kernel_nofault(dentry, dentry_ptr)) {
- pr_warn("aops:%ps with invalid dentry %px\n", a_ops,
- dentry_ptr);
+ pr_warn("aops:%ps ino:%lx with invalid dentry %px\n",
+ a_ops, ino, dentry_ptr);
} else {
/*
* if dentry is corrupted, the %pd handler may still
@@ -158,7 +160,7 @@ void __dump_page(struct page *page, cons
* corrupted struct page
*/
pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n",
- a_ops, host->i_ino, &dentry);
+ a_ops, ino, &dentry);
}
}
out_mapping:
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-debug-do-not-dereference-i_ino-blindly.patch
mm-account-pmd-tables-like-pte-tables.patch
