Commit 45089437 authored by Josef Bacik's avatar Josef Bacik Committed by Linus Torvalds

proc: use kvzalloc for our kernel buffer

Since

  sysctl: pass kernel pointers to ->proc_handler

we have been pre-allocating a buffer to copy the data from the proc
handlers into, and then copying that to userspace.  The problem is this
just blindly kzalloc()'s the buffer size passed in from the read, which in
the case of our 'cat' binary was 64kib.  Order-4 allocations are not
awesome, and since we can potentially allocate up to our maximum order, so
use kvzalloc for these buffers.

[willy@infradead.org: changelog tweaks]

Link: https://lkml.kernel.org/r/6345270a2c1160b89dd5e6715461f388176899d1.1612972413.git.josef@toxicpanda.com
Fixes: 32927393 ("sysctl: pass kernel pointers to ->proc_handler")
Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
CC: Matthew Wilcox <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 152c432b
......@@ -571,7 +571,7 @@ static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter,
error = -ENOMEM;
if (count >= KMALLOC_MAX_SIZE)
goto out;
kbuf = kzalloc(count + 1, GFP_KERNEL);
kbuf = kvzalloc(count + 1, GFP_KERNEL);
if (!kbuf)
goto out;
......@@ -600,7 +600,7 @@ static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter,
error = count;
out_free_buf:
kfree(kbuf);
kvfree(kbuf);
out:
sysctl_head_finish(head);
......
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