The patch titled
Subject: proc: use kvzalloc for our kernel buffer
has been added to the -mm tree. Its filename is
proc-use-vmalloc-for-our-kernel-buffer.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/proc-use-vmalloc-for-our-kernel-buffer.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/proc-use-vmalloc-for-our-kernel-buffer.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Josef Bacik <josef@xxxxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxx: changelog tweaks]
Link: https://lkml.kernel.org/r/6345270a2c1160b89dd5e6715461f388176899d1.1612972413.git.josef@xxxxxxxxxxxxxx
Fixes: 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
CC: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/proc_sysctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/proc/proc_sysctl.c~proc-use-vmalloc-for-our-kernel-buffer
+++ a/fs/proc/proc_sysctl.c
@@ -571,7 +571,7 @@ static ssize_t proc_sys_call_handler(str
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(str
error = count;
out_free_buf:
- kfree(kbuf);
+ kvfree(kbuf);
out:
sysctl_head_finish(head);
_
Patches currently in -mm which might be from josef@xxxxxxxxxxxxxx are
proc-use-vmalloc-for-our-kernel-buffer.patch
