On 2024/9/27 16:22, Aleksandr Mikhalitsyn wrote:
On Fri, Sep 27, 2024 at 8:39 AM <libaokun@xxxxxxxxxxxxxxx> wrote:From: Baokun Li <libaokun1@xxxxxxxxxx> Wesley reported an issue: ================================================================== EXT4-fs (dm-5): resizing filesystem from 7168 to 786432 blocks ------------[ cut here ]------------ kernel BUG at fs/ext4/resize.c:324! CPU: 9 UID: 0 PID: 3576 Comm: resize2fs Not tainted 6.11.0+ #27 RIP: 0010:ext4_resize_fs+0x1212/0x12d0 Call Trace: __ext4_ioctl+0x4e0/0x1800 ext4_ioctl+0x12/0x20 __x64_sys_ioctl+0x99/0xd0 x64_sys_call+0x1206/0x20d0 do_syscall_64+0x72/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e ================================================================== While reviewing the patch, Honza found that when adjusting resize_bg in alloc_flex_gd(), it was possible for flex_gd->resize_bg to be bigger than flexbg_size. The reproduction of the problem requires the following: o_group = flexbg_size * 2 * n; o_size = (o_group + 1) * group_size; n_group: [o_group + flexbg_size, o_group + flexbg_size * 2) o_size = (n_group + 1) * group_size; Take n=0,flexbg_size=16 as an example: last:15 |o---------------|--------------n-| o_group:0 resize to n_group:30 The corresponding reproducer is: img=test.img truncate -s 600M $img mkfs.ext4 -F $img -b 1024 -G 16 8M dev=`losetup -f --show $img` mkdir -p /tmp/test mount $dev /tmp/test resize2fs $dev 248M Delete the problematic plus 1 to fix the issue, and add a WARN_ON_ONCE() to prevent the issue from happening again. Reported-by: Wesley Hershberger <wesley.hershberger@xxxxxxxxxxxxx> Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2081231 Reported-by: Stéphane Graber <stgraber@xxxxxxxxxxxx> Closes: https://lore.kernel.org/all/20240925143325.518508-1-aleksandr.mikhalitsyn@xxxxxxxxxxxxx/ Tested-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx> Tested-by: Eric Sandeen <sandeen@xxxxxxxxxx> Fixes: 665d3e0af4d3 ("ext4: reduce unnecessary memory allocation in alloc_flex_gd()") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>Thanks, Baokun! JFYI, I'm on the way to submit a test to xfstests suite. Kind regards, Alex
Okay. Thanks for doing this. Cheers, Baokun
--- fs/ext4/resize.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index e04eb08b9060..397970121d43 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -253,9 +253,9 @@ static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned int flexbg_size, /* Avoid allocating large 'groups' array if not needed */ last_group = o_group | (flex_gd->resize_bg - 1); if (n_group <= last_group) - flex_gd->resize_bg = 1 << fls(n_group - o_group + 1); + flex_gd->resize_bg = 1 << fls(n_group - o_group); else if (n_group - last_group < flex_gd->resize_bg) - flex_gd->resize_bg = 1 << max(fls(last_group - o_group + 1), + flex_gd->resize_bg = 1 << max(fls(last_group - o_group), fls(n_group - last_group)); flex_gd->groups = kmalloc_array(flex_gd->resize_bg, -- 2.46.0
-- With Best Regards, Baokun Li
