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| author | Hao Lee <haolee.swjtu@gmail.com> | 2022-03-24 00:05:20 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-03-24 03:00:33 +0100 |
| commit | 3a72917ccfbb2eecabefc86aade8acd4a1e85888 (patch) | |
| tree | a08cbeb6bcba18c9553b5d517d3146d7e196a814 /fs/proc | |
| parent | Linux 5.17 (diff) | |
| download | linux-3a72917ccfbb2eecabefc86aade8acd4a1e85888.tar.xz linux-3a72917ccfbb2eecabefc86aade8acd4a1e85888.zip | |
proc: alloc PATH_MAX bytes for /proc/${pid}/fd/ symlinks
It's not a standard approach that use __get_free_page() to alloc path
buffer directly. We'd better use kmalloc and PATH_MAX.
PAGE_SIZE is different on different archs. An unlinked file
with very long canonical pathname will readlink differently
because "(deleted)" eats into a buffer. --adobriyan
[akpm@linux-foundation.org: remove now-unneeded cast]
Link: https://lkml.kernel.org/r/Ye1fCxyZZ0I5lgOL@localhost.localdomain
Signed-off-by: Hao Lee <haolee.swjtu@gmail.com>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/base.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index d654ce7150fd..76bf1aa3cfe8 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1764,25 +1764,25 @@ out: static int do_proc_readlink(struct path *path, char __user *buffer, int buflen) { - char *tmp = (char *)__get_free_page(GFP_KERNEL); + char *tmp = kmalloc(PATH_MAX, GFP_KERNEL); char *pathname; int len; if (!tmp) return -ENOMEM; - pathname = d_path(path, tmp, PAGE_SIZE); + pathname = d_path(path, tmp, PATH_MAX); len = PTR_ERR(pathname); if (IS_ERR(pathname)) goto out; - len = tmp + PAGE_SIZE - 1 - pathname; + len = tmp + PATH_MAX - 1 - pathname; if (len > buflen) len = buflen; if (copy_to_user(buffer, pathname, len)) len = -EFAULT; out: - free_page((unsigned long)tmp); + kfree(tmp); return len; } |