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Message-ID: <864b67a3-6a4a-2afb-8275-b8532ea3cb8f@huawei.com> Date: Sat, 27 Jan 2024 10:07:18 +0800 From: Zhang Yi <yi.zhang@...wei.com> To: Baokun Li <libaokun1@...wei.com>, <linux-ext4@...r.kernel.org> CC: <tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>, <ritesh.list@...il.com>, <linux-kernel@...r.kernel.org>, <yangerkun@...wei.com>, <chengzhihao1@...wei.com>, <yukuai3@...wei.com>, <stable@...r.kernel.org> Subject: Re: [PATCH 4/7] ext4: add positive int attr pointer to avoid sysfs variables overflow On 2024/1/26 16:57, Baokun Li wrote: > We can easily trigger a BUG_ON by using the following commands: > > mount /dev/$disk /tmp/test > echo 2147483650 > /sys/fs/ext4/$disk/mb_group_prealloc > echo test > /tmp/test/file && sync > > ================================================================== > kernel BUG at fs/ext4/mballoc.c:2029! > invalid opcode: 0000 [#1] PREEMPT SMP PTI > CPU: 3 PID: 320 Comm: kworker/u36:1 Not tainted 6.8.0-rc1 #462 > RIP: 0010:mb_mark_used+0x358/0x370 > [...] > Call Trace: > ext4_mb_use_best_found+0x56/0x140 > ext4_mb_complex_scan_group+0x196/0x2f0 > ext4_mb_regular_allocator+0xa92/0xf00 > ext4_mb_new_blocks+0x302/0xbc0 > ext4_ext_map_blocks+0x95a/0xef0 > ext4_map_blocks+0x2b1/0x680 > ext4_do_writepages+0x733/0xbd0 > [...] > ================================================================== > > In ext4_mb_normalize_group_request(): > ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc; > > Here fe_len is of type int, but s_mb_group_prealloc is of type unsigned > int, so setting s_mb_group_prealloc to 2147483650 overflows fe_len to a > negative number, which ultimately triggers a BUG_ON() in mb_mark_used(). > > Therefore, we add attr_pointer_pi (aka positive int attr pointer) with a > value range of 0-INT_MAX to avoid the above problem. In addition to the > mb_group_prealloc sysfs interface, the following interfaces also have uint > to int conversions that result in overflows, and are also fixed. > > err_ratelimit_burst > msg_ratelimit_burst > warning_ratelimit_burst > err_ratelimit_interval_ms > msg_ratelimit_interval_ms > warning_ratelimit_interval_ms > mb_best_avail_max_trim_order > > CC: stable@...r.kernel.org > Signed-off-by: Baokun Li <libaokun1@...wei.com> Looks good to me. Reviewed-by: Zhang Yi <yi.zhang@...wei.com> > --- > fs/ext4/sysfs.c | 25 +++++++++++++++++-------- > 1 file changed, 17 insertions(+), 8 deletions(-) > > diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c > index a5d657fa05cb..6f9f96e00f2f 100644 > --- a/fs/ext4/sysfs.c > +++ b/fs/ext4/sysfs.c > @@ -30,6 +30,7 @@ typedef enum { > attr_first_error_time, > attr_last_error_time, > attr_feature, > + attr_pointer_pi, > attr_pointer_ui, > attr_pointer_ul, > attr_pointer_u64, > @@ -178,6 +179,9 @@ static struct ext4_attr ext4_attr_##_name = { \ > #define EXT4_RO_ATTR_ES_STRING(_name,_elname,_size) \ > EXT4_ATTR_STRING(_name, 0444, _size, ext4_super_block, _elname) > > +#define EXT4_RW_ATTR_SBI_PI(_name,_elname) \ > + EXT4_ATTR_OFFSET(_name, 0644, pointer_pi, ext4_sb_info, _elname) > + > #define EXT4_RW_ATTR_SBI_UI(_name,_elname) \ > EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname) > > @@ -213,17 +217,17 @@ EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan); > EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan); > EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs); > EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request); > -EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc); > +EXT4_RW_ATTR_SBI_PI(mb_group_prealloc, s_mb_group_prealloc); > EXT4_RW_ATTR_SBI_UI(mb_max_linear_groups, s_mb_max_linear_groups); > EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb); > EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error); > -EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval); > -EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst); > -EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval); > -EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst); > -EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval); > -EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst); > -EXT4_RW_ATTR_SBI_UI(mb_best_avail_max_trim_order, s_mb_best_avail_max_trim_order); > +EXT4_RW_ATTR_SBI_PI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval); > +EXT4_RW_ATTR_SBI_PI(err_ratelimit_burst, s_err_ratelimit_state.burst); > +EXT4_RW_ATTR_SBI_PI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval); > +EXT4_RW_ATTR_SBI_PI(warning_ratelimit_burst, s_warning_ratelimit_state.burst); > +EXT4_RW_ATTR_SBI_PI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval); > +EXT4_RW_ATTR_SBI_PI(msg_ratelimit_burst, s_msg_ratelimit_state.burst); > +EXT4_RW_ATTR_SBI_PI(mb_best_avail_max_trim_order, s_mb_best_avail_max_trim_order); > #ifdef CONFIG_EXT4_DEBUG > EXT4_RW_ATTR_SBI_UL(simulate_fail, s_simulate_fail); > #endif > @@ -376,6 +380,7 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a, > > switch (a->attr_id) { > case attr_inode_readahead: > + case attr_pointer_pi: > case attr_pointer_ui: > if (a->attr_ptr == ptr_ext4_super_block_offset) > return sysfs_emit(buf, "%u\n", le32_to_cpup(ptr)); > @@ -448,6 +453,10 @@ static ssize_t ext4_generic_attr_store(struct ext4_attr *a, > return ret; > > switch (a->attr_id) { > + case attr_pointer_pi: > + if ((int)t < 0) > + return -EINVAL; > + fallthrough; > case attr_pointer_ui: > if (t != (unsigned int)t) > return -EINVAL; >
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