From: Yongpeng Yang Date: Fri, 10 Apr 2026 15:05:39 +0000 (+0800) Subject: f2fs: protect extension_list reading with sb_lock in f2fs_sbi_show() X-Git-Url: http://git.ipfire.org/index.cgi?a=commitdiff_plain;h=5909bedbed38c558bee7cb6758ceedf9bc3a9194;p=thirdparty%2Flinux.git f2fs: protect extension_list reading with sb_lock in f2fs_sbi_show() In f2fs_sbi_show(), the extension_list, extension_count and hot_ext_count are read without holding sbi->sb_lock. If a concurrent sysfs store modifies the extension list via f2fs_update_extension_list(), the show path may read inconsistent count and array contents, potentially leading to out-of-bounds access or displaying stale data. Fix this by holding sb_lock around the entire extension list read and format operation. Fixes: b6a06cbbb5f7 ("f2fs: support hot file extension") Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index 969e06b65b04..12993ae1713b 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -387,10 +387,12 @@ static ssize_t f2fs_sbi_show(struct f2fs_attr *a, if (!strcmp(a->attr.name, "extension_list")) { __u8 (*extlist)[F2FS_EXTENSION_LEN] = sbi->raw_super->extension_list; - int cold_count = le32_to_cpu(sbi->raw_super->extension_count); - int hot_count = sbi->raw_super->hot_ext_count; + int cold_count, hot_count; int len = 0, i; + f2fs_down_read(&sbi->sb_lock); + cold_count = le32_to_cpu(sbi->raw_super->extension_count); + hot_count = sbi->raw_super->hot_ext_count; len += sysfs_emit_at(buf, len, "cold file extension:\n"); for (i = 0; i < cold_count; i++) len += sysfs_emit_at(buf, len, "%s\n", extlist[i]); @@ -398,6 +400,7 @@ static ssize_t f2fs_sbi_show(struct f2fs_attr *a, len += sysfs_emit_at(buf, len, "hot file extension:\n"); for (i = cold_count; i < cold_count + hot_count; i++) len += sysfs_emit_at(buf, len, "%s\n", extlist[i]); + f2fs_up_read(&sbi->sb_lock); return len; }