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(ec2-99-79-140-187.ca-central-1.compute.amazonaws.com. [99.79.140.187]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d676761d04sm965825ad.2.2026.08.21.19.39.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Aug 2026 19:39:31 -0700 (PDT) From: hanzhijian To: Alexander Viro , Christian Brauner Cc: Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hanzhijian , syzbot+1c70732df5fd4f0e4fbb@syzkaller.appspotmail.com Subject: [PATCH] fs: fix s_fs_info leak when setup_bdev_super() fails Date: Sat, 22 Aug 2026 10:39:18 +0800 Message-ID: <20260822023918.2498361-1-hanzhijian1991@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" get_tree_bdev_flags() hands fc->s_fs_info to the newly allocated super block in sget_fc() and clears fc->s_fs_info. If setup_bdev_super() then fails (the block device cannot be opened, is read-only, or is frozen), fill_super() is never called and sb->s_root stays NULL. The cleanup path calls deactivate_locked_super(), whose generic_shutdown_super() skips the whole sb->s_root block -- including the put_super() callback that would otherwise release s_fs_info -- leaking the allocation made by the filesystem's init_fs_context(). Hand s_fs_info back to the fs_context when setup_bdev_super() fails so that put_fs_context() releases it through the filesystem's free() callback. Reported-by: syzbot+1c70732df5fd4f0e4fbb@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=3D1c70732df5fd4f0e4fbb Signed-off-by: hanzhijian --- fs/super.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/fs/super.c b/fs/super.c index 05e443173..8b978b67b 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1883,8 +1883,19 @@ int get_tree_bdev_flags(struct fs_context *fc, } } else { error =3D setup_bdev_super(s, fc->sb_flags, fc); - if (!error) - error =3D fill_super(s, fc); + if (error) { + /* + * fill_super() was not called, so nothing has taken + * ownership of fc->s_fs_info. Hand it back so that + * put_fs_context() can release it, otherwise it + * leaks. + */ + fc->s_fs_info =3D s->s_fs_info; + s->s_fs_info =3D NULL; + deactivate_locked_super(s); + return error; + } + error =3D fill_super(s, fc); if (error) { deactivate_locked_super(s); return error; --=20 2.43.0