[PATCH 1/5] zram: do not autocorrect bad recompression parameters

From: Sergey Senozhatsky

Date: Fri Feb 27 2026 - 03:27:55 EST

Do not silently autocorrect bad recompression priority
parameter value and just error out.

Suggested-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 4eaec24a23fe..53e0bbf9d6ec 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -2524,19 +2524,16 @@ static ssize_t recompress_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t len)
{
+ u32 prio = ZRAM_SECONDARY_COMP, prio_max = ZRAM_MAX_COMPS;
struct zram *zram = dev_to_zram(dev);
char *args, *param, *val, *algo = NULL;
u64 num_recomp_pages = ULLONG_MAX;
struct zram_pp_ctl *ctl = NULL;
struct zram_pp_slot *pps;
u32 mode = 0, threshold = 0;
- u32 prio, prio_max;
struct page *page = NULL;
ssize_t ret;

- prio = ZRAM_SECONDARY_COMP;
- prio_max = zram->num_active_comps;
-
args = skip_spaces(buf);
while (*args) {
args = next_arg(args, &param, &val);
@@ -2586,10 +2583,7 @@ static ssize_t recompress_store(struct device *dev,
if (ret)
return ret;

- if (prio == ZRAM_PRIMARY_COMP)
- prio = ZRAM_SECONDARY_COMP;
-
- prio_max = prio + 1;
+ prio_max = min(prio + 1, ZRAM_MAX_COMPS);
continue;
}
}
@@ -2609,7 +2603,7 @@ static ssize_t recompress_store(struct device *dev,
continue;

if (!strcmp(zram->comp_algs[prio], algo)) {
- prio_max = prio + 1;
+ prio_max = min(prio + 1, ZRAM_MAX_COMPS);
found = true;
break;
}
@@ -2627,6 +2621,11 @@ static ssize_t recompress_store(struct device *dev,
goto out;
}

+ if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS) {
+ ret = -EINVAL;
+ goto out;
+ }
+
page = alloc_page(GFP_KERNEL);
if (!page) {
ret = -ENOMEM;
--
2.53.0.473.g4a7958ca14-goog