+ zram-validate-deflate-params.patch added to mm-new branch

The patch titled
     Subject: zram: validate deflate params
has been added to the -mm mm-new branch.  Its filename is
     zram-validate-deflate-params.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-validate-deflate-params.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Sergey Senozhatsky <[email protected]>
Subject: zram: validate deflate params
Date: Wed, 29 Jul 2026 13:57:36 +0900

We must validate user-supplied deflate winbits before we pass it to
zlib_deflate_workspacesize(), which triggers BUG_ON() if winbits value is
outside of valid ranges.

Link: https://lore.kernel.org/[email protected]
Fixes: dc75a0d93bd5 ("zram: support deflate-specific params")
Link: https://sashiko.dev/#/patchset/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Haoqin Huang <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 drivers/block/zram/backend_deflate.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/block/zram/backend_deflate.c~zram-validate-deflate-params
+++ a/drivers/block/zram/backend_deflate.c
@@ -24,8 +24,16 @@ static int deflate_setup_params(struct z
 {
 	if (params->level == ZCOMP_PARAM_NOT_SET)
 		params->level = Z_DEFAULT_COMPRESSION;
-	if (params->deflate.winbits == ZCOMP_PARAM_NOT_SET)
+	if (params->deflate.winbits == ZCOMP_PARAM_NOT_SET) {
 		params->deflate.winbits = DEFLATE_DEF_WINBITS;
+	} else {
+		s32 wb = params->deflate.winbits;
+
+		if ((wb < -15 || wb > -9) && (wb < 9 || wb > 15)) {
+			pr_err("invalid deflate winbits: %d\n", wb);
+			return -EINVAL;
+		}
+	}
 
 	return 0;
 }
_

Patches currently in -mm which might be from [email protected] are

documentation-zram-remove-sections-numbering.patch
zram-set-default-primary-compressor-in-zram_destroy_comps.patch
zram-validate-deflate-params.patch