Patch "module/decompress: use vmalloc() for gzip decompression workspace" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    module/decompress: use vmalloc() for gzip decompression workspace

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     module-decompress-use-vmalloc-for-gzip-decompression.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 823985712279298b57254450f5534d6b8dde1808
Author: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
Date:   Wed Aug 30 17:58:20 2023 +0200

    module/decompress: use vmalloc() for gzip decompression workspace
    
    [ Upstream commit 3737df782c740b944912ed93420c57344b1cf864 ]
    
    Use a similar approach as commit a419beac4a07 ("module/decompress: use
    vmalloc() for zstd decompression workspace") and replace kmalloc() with
    vmalloc() also for the gzip module decompression workspace.
    
    In this case the workspace is represented by struct inflate_workspace
    that can be fairly large for kmalloc() and it can potentially lead to
    allocation errors on certain systems:
    
    $ pahole inflate_workspace
    struct inflate_workspace {
            struct inflate_state       inflate_state;        /*     0  9544 */
            /* --- cacheline 149 boundary (9536 bytes) was 8 bytes ago --- */
            unsigned char              working_window[32768]; /*  9544 32768 */
    
            /* size: 42312, cachelines: 662, members: 2 */
            /* last cacheline: 8 bytes */
    };
    
    Considering that there is no need to use continuous physical memory,
    simply switch to vmalloc() to provide a more reliable in-kernel module
    decompression.
    
    Fixes: b1ae6dc41eaa ("module: add in-kernel support for decompressing")
    Signed-off-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
    Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
index 87440f714c0ca..4156d59be4408 100644
--- a/kernel/module/decompress.c
+++ b/kernel/module/decompress.c
@@ -100,7 +100,7 @@ static ssize_t module_gzip_decompress(struct load_info *info,
 	s.next_in = buf + gzip_hdr_len;
 	s.avail_in = size - gzip_hdr_len;
 
-	s.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
+	s.workspace = vmalloc(zlib_inflate_workspacesize());
 	if (!s.workspace)
 		return -ENOMEM;
 
@@ -138,7 +138,7 @@ static ssize_t module_gzip_decompress(struct load_info *info,
 out_inflate_end:
 	zlib_inflateEnd(&s);
 out:
-	kfree(s.workspace);
+	vfree(s.workspace);
 	return retval;
 }
 #elif defined(CONFIG_MODULE_COMPRESS_XZ)