[PATCH] jfs: replace hardcoded magic number with DTPAGEMAXSLOT constant

[PATCH] jfs: replace hardcoded magic number with DTPAGEMAXSLOT constant

[Zheng Yu]

Replace hardcoded value 127 with DTPAGEMAXSLOT constant in boundary
checks within jfs_readdir() and dtReadFirst(). This improves code
maintainability and ensures consistency with the defined maximum
slot value.

Fixes: ca84a2c9be48 ("jfs: array-index-out-of-bounds fix in dtReadFirst")
Fixes: 839f102efb16 ("jfs: fix array-index-out-of-bounds in jfs_readdir")
Signed-off-by: Zheng Yu <zheng.yu@northwestern.edu>
---
 fs/jfs/jfs_dtree.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
index ab11849cf9cc..0ab83bb7bbdf 100644
--- a/fs/jfs/jfs_dtree.c
+++ b/fs/jfs/jfs_dtree.c
@@ -2903,7 +2903,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
                 stbl = DT_GETSTBL(p);
 
                 for (i = index; i < p->header.nextindex; i++) {
-                       if (stbl[i] < 0 || stbl[i] > 127) {
+                       if (stbl[i] < 0 || stbl[i] >= DTPAGEMAXSLOT) {
                                 jfs_err("JFS: Invalid stbl[%d] = %d for inode %ld, block = %lld",
                                         i, stbl[i], (long)ip->i_ino, (long long)bn);
                                 free_page(dirent_buf);
@@ -3108,7 +3108,7 @@ static int dtReadFirst(struct inode *ip, struct btstack * btstack)
                 /* get the leftmost entry */
                 stbl = DT_GETSTBL(p);
 
-               if (stbl[0] < 0 || stbl[0] > 127) {
+               if (stbl[0] < 0 || stbl[0] >= DTPAGEMAXSLOT) {
                         DT_PUTPAGE(mp);
                         jfs_error(ip->i_sb, "stbl[0] out of bound\n");
                         return -EIO;
--
2.43.0

Re: [PATCH] jfs: replace hardcoded magic number with DTPAGEMAXSLOT constant

[Dave Kleikamp]

Looks good. I'll apply and test this.

I'm removing the Fixes: lines because this is cosmetic and not really a 
bug fix. There's no need to flag this for stable.

Thanks,
Shaggy

On 7/29/25 1:28PM, Zheng Yu wrote:
> Replace hardcoded value 127 with DTPAGEMAXSLOT constant in boundary
> checks within jfs_readdir() and dtReadFirst(). This improves code
> maintainability and ensures consistency with the defined maximum
> slot value.
> 
> Fixes: ca84a2c9be48 ("jfs: array-index-out-of-bounds fix in dtReadFirst")
> Fixes: 839f102efb16 ("jfs: fix array-index-out-of-bounds in jfs_readdir")
> Signed-off-by: Zheng Yu <zheng.yu@northwestern.edu>
> ---
>   fs/jfs/jfs_dtree.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
> index ab11849cf9cc..0ab83bb7bbdf 100644
> --- a/fs/jfs/jfs_dtree.c
> +++ b/fs/jfs/jfs_dtree.c
> @@ -2903,7 +2903,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
>                   stbl = DT_GETSTBL(p);
>   
>                   for (i = index; i < p->header.nextindex; i++) {
> -                       if (stbl[i] < 0 || stbl[i] > 127) {
> +                       if (stbl[i] < 0 || stbl[i] >= DTPAGEMAXSLOT) {
>                                   jfs_err("JFS: Invalid stbl[%d] = %d for inode %ld, block = %lld",
>                                           i, stbl[i], (long)ip->i_ino, (long long)bn);
>                                   free_page(dirent_buf);
> @@ -3108,7 +3108,7 @@ static int dtReadFirst(struct inode *ip, struct btstack * btstack)
>                   /* get the leftmost entry */
>                   stbl = DT_GETSTBL(p);
>   
> -               if (stbl[0] < 0 || stbl[0] > 127) {
> +               if (stbl[0] < 0 || stbl[0] >= DTPAGEMAXSLOT) {
>                           DT_PUTPAGE(mp);
>                           jfs_error(ip->i_sb, "stbl[0] out of bound\n");
>                           return -EIO;
> --
> 2.43.0