CVE-2024-46853

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

spi: nxp-fspi: fix the KASAN report out-of-bounds bug

Change the memcpy length to fix the out-of-bounds issue when writing the data that is not 4 byte aligned to TX FIFO.

To reproduce the issue, write 3 bytes data to NOR chip.

dd if=3b of=/dev/mtd0 [ 36.926103] ================================================================== [ 36.933409] BUG: KASAN: slab-out-of-bounds in nxp_fspi_exec_op+0x26ec/0x2838 [ 36.940514] Read of size 4 at addr ffff00081037c2a0 by task dd/455 [ 36.946721] [ 36.948235] CPU: 3 UID: 0 PID: 455 Comm: dd Not tainted 6.11.0-rc5-gc7b0e37c8434 #1070 [ 36.956185] Hardware name: Freescale i.MX8QM MEK (DT) [ 36.961260] Call trace: [ 36.963723] dump_backtrace+0x90/0xe8 [ 36.967414] show_stack+0x18/0x24 [ 36.970749] dump_stack_lvl+0x78/0x90 [ 36.974451] print_report+0x114/0x5cc [ 36.978151] kasan_report+0xa4/0xf0 [ 36.981670] __asan_report_load_n_noabort+0x1c/0x28 [ 36.986587] nxp_fspi_exec_op+0x26ec/0x2838 [ 36.990800] spi_mem_exec_op+0x8ec/0xd30 [ 36.994762] spi_mem_no_dirmap_read+0x190/0x1e0 [ 36.999323] spi_mem_dirmap_write+0x238/0x32c [ 37.003710] spi_nor_write_data+0x220/0x374 [ 37.007932] spi_nor_write+0x110/0x2e8 [ 37.011711] mtd_write_oob_std+0x154/0x1f0 [ 37.015838] mtd_write_oob+0x104/0x1d0 [ 37.019617] mtd_write+0xb8/0x12c [ 37.022953] mtdchar_write+0x224/0x47c [ 37.026732] vfs_write+0x1e4/0x8c8 [ 37.030163] ksys_write+0xec/0x1d0 [ 37.033586] __arm64_sys_write+0x6c/0x9c [ 37.037539] invoke_syscall+0x6c/0x258 [ 37.041327] el0_svc_common.constprop.0+0x160/0x22c [ 37.046244] do_el0_svc+0x44/0x5c [ 37.049589] el0_svc+0x38/0x78 [ 37.052681] el0t_64_sync_handler+0x13c/0x158 [ 37.057077] el0t_64_sync+0x190/0x194 [ 37.060775] [ 37.062274] Allocated by task 455: [ 37.065701] kasan_save_stack+0x2c/0x54 [ 37.069570] kasan_save_track+0x20/0x3c [ 37.073438] kasan_save_alloc_info+0x40/0x54 [ 37.077736] __kasan_kmalloc+0xa0/0xb8 [ 37.081515] __kmalloc_noprof+0x158/0x2f8 [ 37.085563] mtd_kmalloc_up_to+0x120/0x154 [ 37.089690] mtdchar_write+0x130/0x47c [ 37.093469] vfs_write+0x1e4/0x8c8 [ 37.096901] ksys_write+0xec/0x1d0 [ 37.100332] __arm64_sys_write+0x6c/0x9c [ 37.104287] invoke_syscall+0x6c/0x258 [ 37.108064] el0_svc_common.constprop.0+0x160/0x22c [ 37.112972] do_el0_svc+0x44/0x5c [ 37.116319] el0_svc+0x38/0x78 [ 37.119401] el0t_64_sync_handler+0x13c/0x158 [ 37.123788] el0t_64_sync+0x190/0x194 [ 37.127474] [ 37.128977] The buggy address belongs to the object at ffff00081037c2a0 [ 37.128977] which belongs to the cache kmalloc-8 of size 8 [ 37.141177] The buggy address is located 0 bytes inside of [ 37.141177] allocated 3-byte region [ffff00081037c2a0, ffff00081037c2a3) [ 37.153465] [ 37.154971] The buggy address belongs to the physical page: [ 37.160559] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x89037c [ 37.168596] flags: 0xbfffe0000000000(node=0|zone=2|lastcpupid=0x1ffff) [ 37.175149] page_type: 0xfdffffff(slab) [ 37.179021] raw: 0bfffe0000000000 ffff000800002500 dead000000000122 0000000000000000 [ 37.186788] raw: 0000000000000000 0000000080800080 00000001fdffffff 0000000000000000 [ 37.194553] page dumped because: kasan: bad access detected [ 37.200144] [ 37.201647] Memory state around the buggy address: [ 37.206460] ffff00081037c180: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc [ 37.213701] ffff00081037c200: fa fc fc fc 05 fc fc fc 03 fc fc fc 02 fc fc fc [ 37.220946] >ffff00081037c280: 06 fc fc fc 03 fc fc fc fc fc fc fc fc fc fc fc [ 37.228186] ^ [ 37.232473] ffff00081037c300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 37.239718] ffff00081037c380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 37.246962] ============================================================== —truncated—

Weakness

The product writes data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

• For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.

• Be wary that a language’s interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

• Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.

• Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.

• D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.

• Consider adhering to the following rules when allocating and managing an application’s memory:

• Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.

• Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.

• For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

• Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.

• For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].

References

• https://git.kernel.org/stable/c/09af8b0ba70072be831f3ec459f4063d570f9e24
• https://git.kernel.org/stable/c/2a8787c1cdc7be24fdd8953ecd1a8743a1006235
• https://git.kernel.org/stable/c/491f9646f7ac31af5fca71be1a3e5eb8aa7663ad
• https://git.kernel.org/stable/c/609260542cf86b459c57618b8cdec8020394b7ad
• https://git.kernel.org/stable/c/aa05db44db5f409f6d91c27b5737efb49fb45d9f
• https://git.kernel.org/stable/c/af9ca9ca3e44f48b2a191e100d452fbf850c3d87
• https://git.kernel.org/stable/c/d1a1dfcec77c57b1181da93d11a3db1bc4eefa97
• https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html
• https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html