mmc: core: Add validation for host-provided max_segs
Summary
| CVE | CVE-2026-98884 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-10-23 12:18:22 UTC |
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| Updated | 2026-10-23 12:18:22 UTC |
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| Description | In the Linux kernel, the following vulnerability has been resolved:
mmc: core: Add validation for host-provided max_segs
The max_segs field is of type unsigned short, and if a host driver
sets an excessively large value, it may be truncated to zero. This
can cause mmc_alloc_sg() to call kmalloc_objs() with a zero size
allocation request, which leads to undefined behavior.
Under the SLUB allocator, kmalloc(0) returns a special pointer
(ZERO_SIZE_PTR). The subsequent 'if (sg)' check will evaluate to
true, and sg_init_table() will then attempt to access invalid memory,
resulting in a crash:
dwmmc_rockchip 2a310000.mmc: Successfully tuned phase to 133
mmc1: new UHS-I speed SDR104 SDHC card at address aaaa
Unable to handle kernel paging request at virtual address 0000001ffffffff0
Mem abort info:
ESR = 0x0000000096000004
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000102c88000
[0000001ffffffff0] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000004 [#1] SMP
Modules linked in:
CPU: 2 UID: 0 PID: 102 Comm: kworker/2:1 Not tainted 7.0.0-rc6-next-20260331-00013-g4d93c25963c5-dirty #80 PREEMPT
Hardware name: Rockchip RK3576 EVB V10 Board (DT)
Workqueue: events_freezable mmc_rescan
pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : sg_init_table+0x2c/0x50
lr : sg_init_table+0x24/0x50
sp : ffff8000837db710
x29: ffff8000837db710 x28: 000000000000c000 x27: 0000000000000300
x26: 0000000000000000 x25: 0000000000000040 x24: ffff0000c46a0000
x23: 0000000000000000 x22: ffff0000c0c73c00 x21: 0000000000000010
x20: 0000000000000010 x19: 0000000000000000 x18: 000000000000002c
x17: 0000000000000000 x16: 0000000000000001 x15: 0000000000000000
x14: 0000000000000400 x13: ffff8000837dc000 x12: 0000000000000000
x11: ffff0000c0c73ca0 x10: 0000000000000040 x9 : 459ec1f0abbdbb00
x8 : 0000001fffffffe0 x7 : 0000000000000000 x6 : 000000000000003f
x5 : 0000000000035579 x4 : 0000000000000901 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000010
Call trace:
sg_init_table+0x2c/0x50 (P)
mmc_mq_init_request+0x64/0x90
blk_mq_alloc_map_and_rqs+0x3ac/0x480
blk_mq_alloc_set_map_and_rqs+0x98/0x1e0
blk_mq_alloc_tag_set+0x1c0/0x290
mmc_init_queue+0x120/0x370
mmc_blk_alloc_req+0x150/0x420
To prevent this, add a validation check in mmc_mq_init_request() to
detect when sg_len (derived from max_segs) is zero. If sg_len is zero,
we return an error and print an error message, allowing host driver
developers to identify and fix incorrect max_segs configuration.
This is a defensive measure that ensures the MMC core fails gracefully
when host drivers provide invalid max_segs values, rather than crashing
with a page fault. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 03f5a16ec85beebabd5ab5e67ac1527f87908ded git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 c465608bd25d7f8565be7817a6a36a5d69f8aa14 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 a8283f7d93f0d9336b15618b9665279ff6944319 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 9cca3c0c1472d6204ef8a78a6e7b3afe9610b22e git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 b037c2f7794aa01ee2a00e43c29645fd2dd2dfb9 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 3e0483e93a8be320f70a1ff68d835f7f015af311 git |
Not specified |
| CNA |
Linux |
Linux |
affected 5.15.222 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 6.1.189 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 6.6.158 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 6.12.111 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 6.18.53 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 5.15.222 5.15.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.1.189 6.1.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.6.158 6.6.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.111 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.53 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/c465608bd25d7f8565be7817a6a36a5d69f8aa14 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/b037c2f7794aa01ee2a00e43c29645fd2dd2dfb9 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/03f5a16ec85beebabd5ab5e67ac1527f87908ded |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/3e0483e93a8be320f70a1ff68d835f7f015af311 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/a8283f7d93f0d9336b15618b9665279ff6944319 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/9cca3c0c1472d6204ef8a78a6e7b3afe9610b22e |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.