Messages in this thread Patch in this message | | | Date | Fri, 25 Jan 2013 15:09:59 +0800 | From | Li Zefan <> | Subject | [PATCH] cgroup: fix cgroup_path() vs rename() race |
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rename() will change dentry->d_name. The result of this race can be worse than seeing partially rewritten name, but we might access a stale pointer because rename() will re-allocate memory to hold a longer name.
Use dentry_path_raw(), and this vfs API will take care of lockings.
Signed-off-by: Li Zefan <lizefan@huawei.com> --- kernel/cgroup.c | 22 +++------------------- 1 file changed, 3 insertions(+), 19 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 5d4c92e..776ff75 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1792,26 +1792,10 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) return 0; } - start = buf + buflen - 1; + start = dentry_path_raw(dentry, buf, buflen); + if (IS_ERR(start)) + return PTR_ERR(start); - *start = '\0'; - for (;;) { - int len = dentry->d_name.len; - - if ((start -= len) < buf) - return -ENAMETOOLONG; - memcpy(start, dentry->d_name.name, len); - cgrp = cgrp->parent; - if (!cgrp) - break; - - dentry = cgrp->dentry; - if (!cgrp->parent) - continue; - if (--start < buf) - return -ENAMETOOLONG; - *start = '/'; - } memmove(buf, start, buf + buflen - start); return 0; } -- 1.8.0.2
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