test

[Tadeusz Struk]

#syz test: https://android.googlesource.com/kernel/common android12-5.10

======================================================
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index c6800b880920..42d06c68d5c5 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -381,6 +381,12 @@ static inline int exfat_sector_to_cluster(struct exfat_sb_info *sbi,
EXFAT_RESERVED_CLUSTERS;
}

+static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
+ unsigned int clus)
+{
+ return clus >= EXFAT_FIRST_CLUSTER && clus < sbi->num_clusters;
+}
+
/* super.c */
int exfat_set_volume_dirty(struct super_block *sb);
int exfat_clear_volume_dirty(struct super_block *sb);
diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c
index a3464e56a7e1..421c27353104 100644
--- a/fs/exfat/fatent.c
+++ b/fs/exfat/fatent.c
@@ -81,12 +81,6 @@ int exfat_ent_set(struct super_block *sb, unsigned int loc,
return 0;
}

-static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
- unsigned int clus)
-{
- return clus >= EXFAT_FIRST_CLUSTER && clus < sbi->num_clusters;
-}
-
int exfat_ent_get(struct super_block *sb, unsigned int loc,
unsigned int *content)
{
diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
index 03f142307174..92f5b5b5a0d0 100644
--- a/fs/exfat/balloc.c
+++ b/fs/exfat/balloc.c
@@ -149,6 +149,9 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
struct exfat_sb_info *sbi = EXFAT_SB(sb);

WARN_ON(clu < EXFAT_FIRST_CLUSTER);
+ if (!is_valid_cluster(sbi, clu))
+ return -EINVAL;
+
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
@@ -167,6 +170,9 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
struct exfat_mount_options *opts = &sbi->options;

WARN_ON(clu < EXFAT_FIRST_CLUSTER);
+ if (!is_valid_cluster(sbi, clu))
+ return;
+
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
--
2.36.1

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
checking file fs/exfat/exfat_fs.h
Hunk #1 succeeded at 380 (offset -1 lines).
checking file fs/exfat/fatent.c
Hunk #1 FAILED at 81.
1 out of 1 hunk FAILED
checking file fs/exfat/balloc.c



Tested on:

commit: 503435dc FROMGIT: usb: gadget: uvc: allow for applicat..
git tree: https://android.googlesource.com/kernel/common android12-5.10
dashboard link: https://syzkaller.appspot.com/bug?extid=a4087e40b9c13aad7892
compiler:
patch: https://syzkaller.appspot.com/x/patch.diff?x=14159cbef00000

[Tadeusz Struk]

#syz test: https://android.googlesource.com/kernel/common android12-5.10

==================================================

diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
index 579c10f57c2b..db35b9ae60f4 100644
--- a/fs/exfat/balloc.c
+++ b/fs/exfat/balloc.c
@@ -149,6 +149,9 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu)

struct exfat_sb_info *sbi = EXFAT_SB(sb);

WARN_ON(clu < EXFAT_FIRST_CLUSTER);
+ if (!is_valid_cluster(sbi, clu))
+ return -EINVAL;
+
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);

@@ -167,6 +170,9 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu)

struct exfat_mount_options *opts = &sbi->options;

WARN_ON(clu < EXFAT_FIRST_CLUSTER);
+ if (!is_valid_cluster(sbi, clu))
+ return;
+
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index b8f0e829ecbd..0d139c7d150d 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -380,6 +380,14 @@ static inline int exfat_sector_to_cluster(struct exfat_sb_info *sbi,

EXFAT_RESERVED_CLUSTERS;
}

+static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
+ unsigned int clus)
+{

+ if (clus < EXFAT_FIRST_CLUSTER || sbi->num_clusters <= clus)
+ return false;
+ return true;

+}
+
/* super.c */
int exfat_set_volume_dirty(struct super_block *sb);
int exfat_clear_volume_dirty(struct super_block *sb);
diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c

index c3c9afee7418..a1481e47a761 100644
--- a/fs/exfat/fatent.c
+++ b/fs/exfat/fatent.c
@@ -81,14 +81,6 @@ int exfat_ent_set(struct super_block *sb, unsigned int loc,

return 0;
}

-static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
- unsigned int clus)
-{

- if (clus < EXFAT_FIRST_CLUSTER || sbi->num_clusters <= clus)
- return false;
- return true;

-}
-
int exfat_ent_get(struct super_block *sb, unsigned int loc,
unsigned int *content)
{

--
2.36.1

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+a4087e...@syzkaller.appspotmail.com

Tested on:

commit: 503435dc FROMGIT: usb: gadget: uvc: allow for applicat..
git tree: https://android.googlesource.com/kernel/common android12-5.10

kernel config: https://syzkaller.appspot.com/x/.config?x=95671325401eb9fb
dashboard link: https://syzkaller.appspot.com/bug?extid=a4087e40b9c13aad7892
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=1374cf49f00000

Note: testing is done by a robot and is best-effort only.