kernfs: fix ino wrap-around detection
commit5.4-rM2-2.2.x-imx-squashede23f568aa6
upstream. When the 32bit ino wraps around, kernfs increments the generation number to distinguish reused ino instances. The wrap-around detection tests whether the allocated ino is lower than what the cursor but the cursor is pointing to the next ino to allocate so the condition never triggers. Fix it by remembering the last ino and comparing against that. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Fixes:4a3ef68aca
("kernfs: implement i_generation") Cc: Namhyung Kim <namhyung@kernel.org> Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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451b1d966a
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@ -622,7 +622,6 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
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{
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struct kernfs_node *kn;
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u32 gen;
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int cursor;
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int ret;
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name = kstrdup_const(name, GFP_KERNEL);
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@ -635,11 +634,11 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
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idr_preload(GFP_KERNEL);
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spin_lock(&kernfs_idr_lock);
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cursor = idr_get_cursor(&root->ino_idr);
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ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
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if (ret >= 0 && ret < cursor)
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if (ret >= 0 && ret < root->last_ino)
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root->next_generation++;
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gen = root->next_generation;
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root->last_ino = ret;
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spin_unlock(&kernfs_idr_lock);
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idr_preload_end();
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if (ret < 0)
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@ -187,6 +187,7 @@ struct kernfs_root {
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/* private fields, do not use outside kernfs proper */
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struct idr ino_idr;
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u32 last_ino;
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u32 next_generation;
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struct kernfs_syscall_ops *syscall_ops;
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