Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read The bound-check in iommufd_veventq_fops_read() for the normal vEVENT path uses sizeof(hdr) where the surrounding code uses sizeof(*hdr): if (!vevent_for_lost_events_header(cur) && sizeof(hdr) + cur->data_len > count - done) { hdr is declared as struct iommufd_vevent_header *, so sizeof(hdr) evaluates to the size of the pointer. Surrounding code uses sizeof(*hdr) consistently: if (done >= count || sizeof(*hdr) > count - done) { ... if (copy_to_user(buf + done, hdr, sizeof(*hdr))) { ... done += sizeof(*hdr); struct iommufd_vevent_header is currently 8 bytes (two __u32 fields, flags and sequence), so on 64-bit (sizeof(void *) == 8) the two expressions happen to be equal and the check works as intended. On 32-bit (sizeof(void *) == 4) the check under-counts the header by 4 bytes: a vEVENT whose data_len causes 8 + cur->data_len to exceed count - done while 4 + cur->data_len does not will pass the check, then the loop will copy_to_user 8 bytes of header followed by data_len bytes of payload, writing past the user-supplied buffer. It is also a latent bug for any future expansion of struct iommufd_vevent_header beyond sizeof(void *) on 64-bit; the check should not depend on the type happening to match the host pointer width. Use sizeof(*hdr) to match the rest of the function and the actual amount that will be copied.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected e36ba5ab808ef6237c3148d469c8238674230e2b before 04a177f91160ee18da98f5689482cf0f589ec869; affected e36ba5ab808ef6237c3148d469c8238674230e2b before 0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72; affected e36ba5ab808ef6237c3148d469c8238674230e2b before be93d186ae88a92e7aa77e122d4e661fa57b1e39 |
| Linux / Linux | affected 6.15; unaffected 0 before 6.15; unaffected 6.18.39 through 6.18.*; unaffected 7.1.4 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/04a177f91160ee18da98f5689482cf0f589ec869
- https://git.kernel.org/stable/c/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72
- https://git.kernel.org/stable/c/be93d186ae88a92e7aa77e122d4e661fa57b1e39
ADP enrichment
No English description supplied.
No references supplied.