CVE-2025-38179

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

smb: client: fix max_sge overflow in smb_extract_folioq_to_rdma()

This fixes the following problem:

[ 749.901015] [ T8673] run fstests cifs/001 at 2025-06-17 09:40:30 [ 750.346409] [ T9870] ================================================================== [ 750.346814] [ T9870] BUG: KASAN: slab-out-of-bounds in smb_set_sge+0x2cc/0x3b0 [cifs] [ 750.347330] [ T9870] Write of size 8 at addr ffff888011082890 by task xfs_io/9870 [ 750.347705] [ T9870] [ 750.348077] [ T9870] CPU: 0 UID: 0 PID: 9870 Comm: xfs_io Kdump: loaded Not tainted 6.16.0-rc2-metze.02+ #1 PREEMPT(voluntary) [ 750.348082] [ T9870] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 750.348085] [ T9870] Call Trace: [ 750.348086] [ T9870] [ 750.348088] [ T9870] dump_stack_lvl+0x76/0xa0 [ 750.348106] [ T9870] print_report+0xd1/0x640 [ 750.348116] [ T9870] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 750.348120] [ T9870] ? kasan_complete_mode_report_info+0x26/0x210 [ 750.348124] [ T9870] kasan_report+0xe7/0x130 [ 750.348128] [ T9870] ? smb_set_sge+0x2cc/0x3b0 [cifs] [ 750.348262] [ T9870] ? smb_set_sge+0x2cc/0x3b0 [cifs] [ 750.348377] [ T9870] __asan_report_store8_noabort+0x17/0x30 [ 750.348381] [ T9870] smb_set_sge+0x2cc/0x3b0 [cifs] [ 750.348496] [ T9870] smbd_post_send_iter+0x1990/0x3070 [cifs] [ 750.348625] [ T9870] ? __pfx_smbd_post_send_iter+0x10/0x10 [cifs] [ 750.348741] [ T9870] ? update_stack_state+0x2a0/0x670 [ 750.348749] [ T9870] ? cifs_flush+0x153/0x320 [cifs] [ 750.348870] [ T9870] ? cifs_flush+0x153/0x320 [cifs] [ 750.348990] [ T9870] ? update_stack_state+0x2a0/0x670 [ 750.348995] [ T9870] smbd_send+0x58c/0x9c0 [cifs] [ 750.349117] [ T9870] ? __pfx_smbd_send+0x10/0x10 [cifs] [ 750.349231] [ T9870] ? unwind_get_return_address+0x65/0xb0 [ 750.349235] [ T9870] ? __pfx_stack_trace_consume_entry+0x10/0x10 [ 750.349242] [ T9870] ? arch_stack_walk+0xa7/0x100 [ 750.349250] [ T9870] ? stack_trace_save+0x92/0xd0 [ 750.349254] [ T9870] __smb_send_rqst+0x931/0xec0 [cifs] [ 750.349374] [ T9870] ? kernel_text_address+0x173/0x190 [ 750.349379] [ T9870] ? kasan_save_stack+0x39/0x70 [ 750.349382] [ T9870] ? kasan_save_track+0x18/0x70 [ 750.349385] [ T9870] ? __kasan_slab_alloc+0x9d/0xa0 [ 750.349389] [ T9870] ? __pfx___smb_send_rqst+0x10/0x10 [cifs] [ 750.349508] [ T9870] ? smb2_mid_entry_alloc+0xb4/0x7e0 [cifs] [ 750.349626] [ T9870] ? cifs_call_async+0x277/0xb00 [cifs] [ 750.349746] [ T9870] ? cifs_issue_write+0x256/0x610 [cifs] [ 750.349867] [ T9870] ? netfs_do_issue_write+0xc2/0x340 [netfs] [ 750.349900] [ T9870] ? netfs_advance_write+0x45b/0x1270 [netfs] [ 750.349929] [ T9870] ? netfs_write_folio+0xd6c/0x1be0 [netfs] [ 750.349958] [ T9870] ? netfs_writepages+0x2e9/0xa80 [netfs] [ 750.349987] [ T9870] ? do_writepages+0x21f/0x590 [ 750.349993] [ T9870] ? filemap_fdatawrite_wbc+0xe1/0x140 [ 750.349997] [ T9870] ? entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 750.350002] [ T9870] smb_send_rqst+0x22e/0x2f0 [cifs] [ 750.350131] [ T9870] ? __pfx_smb_send_rqst+0x10/0x10 [cifs] [ 750.350255] [ T9870] ? local_clock_noinstr+0xe/0xd0 [ 750.350261] [ T9870] ? kasan_save_alloc_info+0x37/0x60 [ 750.350268] [ T9870] ? __kasan_check_write+0x14/0x30 [ 750.350271] [ T9870] ? _raw_spin_lock+0x81/0xf0 [ 750.350275] [ T9870] ? __pfx__raw_spin_lock+0x10/0x10 [ 750.350278] [ T9870] ? smb2_setup_async_request+0x293/0x580 [cifs] [ 750.350398] [ T9870] cifs_call_async+0x477/0xb00 [cifs] [ 750.350518] [ T9870] ? __pfx_smb2_writev_callback+0x10/0x10 [cifs] [ 750.350636] [ T9870] ? __pfx_cifs_call_async+0x10/0x10 [cifs] [ 750.350756] [ T9870] ? __pfx__raw_spin_lock+0x10/0x10 [ 750.350760] [ T9870] ? __kasan_check_write+0x14/0x30 [ 750.350763] [ T98 —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/8ae7814589d7bd850294ac14ec4c1725dafd42ca
• https://git.kernel.org/stable/c/a379a8a2a0032e12e7ef397197c9c2ad011588d6
• https://git.kernel.org/stable/c/e0ba9b2f188166550296005e64b15e80db82ad8a