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authorHao Lee <haolee.swjtu@gmail.com>2022-03-23 16:05:20 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-23 19:00:33 -0700
commit3a72917ccfbb2eecabefc86aade8acd4a1e85888 (patch)
treea08cbeb6bcba18c9553b5d517d3146d7e196a814 /fs/proc
parentf443e374ae131c168a065ea1748feac6b2e76613 (diff)
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.c8
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;
}