The patch titled
Subject: proc: revalidate misc dentries
has been added to the -mm tree. Its filename is
proc-revalidate-misc-dentries.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-revalidate-misc-dentries.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-revalidate-misc-dentries.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: proc: revalidate misc dentries
If module removes proc directory while another process pins it by
chdir'ing to it, then subsequent recreation of proc entry and all entries
down the tree will not be visible to any process until pinning process
unchdir from directory and unpins everything.
Steps to reproduce:
proc_mkdir("aaa", NULL);
proc_create("aaa/bbb", ...);
chdir("/proc/aaa");
remove_proc_entry("aaa/bbb", NULL);
remove_proc_entry("aaa", NULL);
proc_mkdir("aaa", NULL);
# inaccessible because "aaa" dentry still points
# to the original "aaa".
proc_create("aaa/bbb", ...);
Fix is to implement ->d_revalidate and ->d_delete.
Link: http://lkml.kernel.org/r/20180312201938.GA4871@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/generic.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff -puN fs/proc/generic.c~proc-revalidate-misc-dentries fs/proc/generic.c
--- a/fs/proc/generic.c~proc-revalidate-misc-dentries
+++ a/fs/proc/generic.c
@@ -15,6 +15,7 @@
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/printk.h>
#include <linux/mount.h>
@@ -219,6 +220,26 @@ void proc_free_inum(unsigned int inum)
ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
}
+static int proc_misc_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ if (flags & LOOKUP_RCU)
+ return -ECHILD;
+
+ if (atomic_read(&PDE(d_inode(dentry))->in_use) < 0)
+ return 0; /* revalidate */
+ return 1;
+}
+
+static int proc_misc_d_delete(const struct dentry *dentry)
+{
+ return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
+}
+
+static const struct dentry_operations proc_misc_dentry_ops = {
+ .d_revalidate = proc_misc_d_revalidate,
+ .d_delete = proc_misc_d_delete,
+};
+
/*
* Don't create negative dentries here, return -ENOENT by hand
* instead.
@@ -236,7 +257,7 @@ struct dentry *proc_lookup_de(struct ino
inode = proc_get_inode(dir->i_sb, de);
if (!inode)
return ERR_PTR(-ENOMEM);
- d_set_d_op(dentry, &simple_dentry_operations);
+ d_set_d_op(dentry, &proc_misc_dentry_ops);
d_add(dentry, inode);
return NULL;
}
_
Patches currently in -mm which might be from adobriyan@xxxxxxxxx are
slab-mark-kmalloc-machinery-as-__ro_after_init.patch
slab-fixup-calculate_alignment-argument-type.patch
slab-make-kmalloc_index-return-unsigned-int.patch
slab-make-kmalloc_size-return-unsigned-int.patch
slab-make-create_kmalloc_cache-work-with-32-bit-sizes.patch
slab-make-create_boot_cache-work-with-32-bit-sizes.patch
slab-make-kmem_cache_create-work-with-32-bit-sizes.patch
slab-make-size_index-array-u8.patch
slab-make-size_index_elem-unsigned-int.patch
slub-make-remote_node_defrag_ratio-unsigned-int.patch
slub-make-max_attr_size-unsigned-int.patch
slub-make-red_left_pad-unsigned-int.patch
slub-make-reserved-unsigned-int.patch
slub-make-align-unsigned-int.patch
slub-make-inuse-unsigned-int.patch
slub-make-cpu_partial-unsigned-int.patch
slub-make-offset-unsigned-int.patch
slub-make-object_size-unsigned-int.patch
slub-make-size-unsigned-int.patch
slab-make-kmem_cache_flags-accept-32-bit-object-size.patch
kasan-make-kasan_cache_create-work-with-32-bit-slab-cache-sizes.patch
slab-make-usercopy-region-32-bit.patch
slub-make-slab_index-return-unsigned-int.patch
slub-make-struct-kmem_cache_order_objects-x-unsigned-int.patch
slub-make-size_from_object-return-unsigned-int.patch
slab-use-32-bit-arithmetic-in-freelist_randomize.patch
proc-do-less-stuff-under-pde_unload_lock.patch
proc-move-proc-sysvipc-creation-to-where-it-belongs.patch
proc-faster-open-close-of-files-without-release-hook.patch
proc-randomize-struct-pde_opener.patch
proc-move-struct-pde_opener-to-kmem-cache.patch
proc-account-struct-pde_opener.patch
proc-check-permissions-earlier-for-proc-wchan.patch
proc-use-set_puts-at-proc-wchan.patch
proc-test-proc-self-wchan.patch
proc-test-proc-self-syscall.patch
proc-move-struct-proc_dir_entry-into-kmem-cache.patch
proc-fix-proc-map_files-lookup-some-more.patch
proc-register-filesystem-last.patch
proc-faster-proc-cmdline.patch
proc-do-mmput-asap-for-proc-map_files.patch
proc-revalidate-misc-dentries.patch
uts-create-struct-uts_namespace-from-kmem_cache.patch
seq_file-delete-small-value-optimization.patch
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