fs/ntfs3: resize log->one_page_buf when adopting on-disk page size

Overview

In the Linux kernel, the following vulnerability has been resolved:

fs/ntfs3: resize log->one_page_buf when adopting on-disk page size

log_replay() allocates log->one_page_buf using the page size that was chosen from the host PAGE_SIZE:

log->one_page_buf = kmalloc(log->page_size, GFP_NOFS);

Later, when a restart area is found, the log page size recorded on disk is adopted:

t32 = le32_to_cpu(log->rst_info.r_page->sys_page_size);
if (log->page_size != t32) {
	log->l_size = log->orig_file_size;
	log->page_size = norm_file_page(t32, &log->l_size,
					t32 == DefaultLogPageSize);
}

If the on-disk page size is larger than the size used for the initial allocation, log->page_size grows but one_page_buf is left at its original, smaller size. A subsequent unaligned read_log_page() then reads log->page_size bytes into the undersized scratch buffer:

page_buf = page_off ? log->one_page_buf : *buffer;
err = ntfs_read_run_nb_ra(ni->mi.sbi, &ni->file.run, page_vbo, page_buf,
			  log->page_size, NULL, &log->read_ahead);

overflowing the allocation. This is reachable when mounting a dirty NTFS volume whose log was formatted with a page size larger than the buffer initially allocated on the mounting host (for example a 64K-log volume mounted on a host that allocated a 4K scratch buffer).

Grow one_page_buf when the adopted on-disk page size exceeds the size used for the initial allocation. On krealloc() failure the original buffer is left intact and freed by the existing error path.

Affected

• Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 220a6ef5e89a11ffd5e490046b86dc9fb6da0e4b
• Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 2097a2537d9d1c29c0e20ed0dbf717a0ccd8f374
• Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < f1422df595d69b997d23a8f11e12c528ccef7fad
• Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 4f129fc6f756f8541e5bff45b1804cc11b1ec712
• Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < c99444f6dfca893f6d310aae4a53c620f98f7b4f
• Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 5a35454179fe1041d9cd286f5d320ce0d448c12a
• Linux 5.15

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.