[PATCH] Prevent entering an infinite loop when i is 0

[PATCH] Prevent entering an infinite loop when i is 0

[liujinbao1]

From: liujinbao1 <liujinbao1@xiaomi.com>

When i=0 and err is not equal to 0,
the while(-1) loop will enter into an
infinite loop. This patch avoids this issue.
---
 fs/erofs/decompressor.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index c2253b6a5416..1b2b8cc7911c 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -539,6 +539,8 @@ int __init z_erofs_init_decompressor(void)
 	for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i) {
 		err = z_erofs_decomp[i] ? z_erofs_decomp[i]->init() : 0;
 		if (err) {
+			if (!i)
+				return err;
 			while (--i)
 				if (z_erofs_decomp[i])
 					z_erofs_decomp[i]->exit();
-- 
2.25.1

Re: [PATCH] Prevent entering an infinite loop when i is 0

[Gao Xiang]

Hi,

On 2024/8/22 14:27, liujinbao1 wrote:
> From: liujinbao1 <liujinbao1@xiaomi.com>
> 
> When i=0 and err is not equal to 0,
> the while(-1) loop will enter into an
> infinite loop. This patch avoids this issue.

Missing your Signed-off-by here.

> ---
>   fs/erofs/decompressor.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
> index c2253b6a5416..1b2b8cc7911c 100644
> --- a/fs/erofs/decompressor.c
> +++ b/fs/erofs/decompressor.c
> @@ -539,6 +539,8 @@ int __init z_erofs_init_decompressor(void)
>   	for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i) {
>   		err = z_erofs_decomp[i] ? z_erofs_decomp[i]->init() : 0;
>   		if (err) {
> +			if (!i)
> +				return err;
>   			while (--i)
>   				if (z_erofs_decomp[i])
>   					z_erofs_decomp[i]->exit();


Thanks for catching this, how about the following diff (space-demaged).

If it looks good to you, could you please send another version?

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index c2253b6a5416..c9b2bc1309d2 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -534,18 +534,16 @@ int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb)

  int __init z_erofs_init_decompressor(void)
  {
-       int i, err;
+       int i, err = 0;

         for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i) {
                 err = z_erofs_decomp[i] ? z_erofs_decomp[i]->init() : 0;
-               if (err) {
+               if (err && i)
                         while (--i)
                                 if (z_erofs_decomp[i])
                                         z_erofs_decomp[i]->exit();
-                       return err;
-               }
         }
-       return 0;
+       return err;
  }