Linux: >> Linux Kernel >> 6.13.5 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
mm: do file ownership checks with the proper mount idmap
Ever since idmapped mounts were introduced, inode ownership checks (for
side-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done
against the nop_mnt_idmap, which completely ignores the file's mount's
idmap. This results in odd edgecases like:
1) mount/bind-mount with an idmap userA:userB:1
2) userB runs an owner_or_capable() check on file that is owned by userA
on-disk/in-memory, but owned by userB after idmap translation
3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied
In the case of mincore/madvise MADV_PAGEOUT, this is usually benign,
because file_permission(file, MAY_WRITE) will probably succeed, as it uses
the proper idmap internally, but it does not need to be the case on e.g a
0444 file where even the owner itself doesn't have permissions to write to
it.
Since this is clearly not trivial to get right, introduce a
file_owner_or_capable() that can carry the correct semantics, and switch
the various users in mm to it.
The issue was found by manual code inspection & an off-list discussion
with Jan Kara.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
exfat: bound uniname advance in exfat_find_dir_entry()
In exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the
output pointer by a fixed amount while the loop guard only tracks the
accumulated name length:
if (++order == 2)
uniname = p_uniname->name;
else
uniname += EXFAT_FILE_NAME_LEN;
len = exfat_extract_uni_name(ep, entry_uniname);
name_len += len;
unichar = *(uniname+len);
*(uniname+len) = 0x0;
uniname grows by EXFAT_FILE_NAME_LEN (15) per name entry, but name_len
grows only by the actual extracted length, which is shorter when a name
fragment contains an early NUL. The only guard is
`name_len >= MAX_NAME_LENGTH`, so a crafted directory with many short
name fragments lets uniname run far past the
p_uniname->name[MAX_NAME_LENGTH + 3] buffer while name_len stays small,
causing an out-of-bounds read and write at *(uniname+len).
The sibling extractor exfat_get_uniname_from_ext_entry() already stops
on a short fragment (the lockstep `len != EXFAT_FILE_NAME_LEN` guard
added in commit d42334578eba ("exfat: check if filename entries exceeds
max filename length")); exfat_find_dir_entry() never got the
equivalent. Track the per-entry write offset as a count and reject a
fragment once the offset, or the offset plus the extracted length, would
exceed MAX_NAME_LENGTH, before forming the output pointer.
CVSS Score
7.8
EPSS Score
0.002
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
module: decompress: check return value of module_extend_max_pages()
module_extend_max_pages() calls kvrealloc() internally and returns
-ENOMEM on allocation failure. The return value is never checked.
If the initial allocation fails, info->pages remains NULL and
info->max_pages remains 0. Subsequent calls to module_get_next_page()
will attempt to dynamically grow the array by calling
module_extend_max_pages(info, 0) since info->used_pages is 0. This
results in kvrealloc(NULL, 0) returning ZERO_SIZE_PTR, which is treated
as a success, leading to a dereference of ZERO_SIZE_PTR and a kernel
oops.
Fix: add the missing error check after module_extend_max_pages() and
return immediately on failure. This matches the pattern used by every
other kvrealloc() caller in the module loading path.
[Sami: Corrected the analysis in the commit message.]
CVSS Score
5.5
EPSS Score
0.002
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
NFSv4: include MAY_WRITE in open permission mask for O_TRUNC
POSIX requires write permission to truncate a file, so an open() that
specifies O_TRUNC must be authorized for write access regardless of the
O_ACCMODE access mode.
nfs_open_permission_mask() builds the access mask passed to
nfs_may_open(), which is the local authorization gate for OPENs the
client serves itself from a cached write delegation via the
can_open_delegated() path in nfs4_try_open_cached(). The mask is
derived from O_ACCMODE alone, so an open(O_RDONLY | O_TRUNC) against a
file the caller cannot write requests only MAY_READ and passes the
local check. The OPEN is then satisfied locally and the truncation is
issued to the server as a SETATTR(size=0) over the delegation stateid,
which the server accepts under standard write-delegation semantics.
POSIX requires that this open fail with EACCES.
Include MAY_WRITE in the mask whenever O_TRUNC is set so the local
check matches the access the server would have enforced.
CVSS Score
7.1
EPSS Score
0.002
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
iommufd: Break the loop on failure in iommufd_fault_fops_read()
On a copy_to_user() failure inside the inner list_for_each_entry, only the
inner loop breaks; the outer while re-fetches the just-restored fault group
and retries the failing copy_to_user() forever, spinning the reader at 100%
CPU with fault->mutex held.
Check rc after the inner loop and break the outer while as well.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
RDMA/siw: bound Read Response placement to the RREAD length
In drivers/infiniband/sw/siw/siw_qp_rx.c, siw_proc_rresp() places each
inbound Read Response DDP segment at sge->laddr + wqe->processed and then
accumulates wqe->processed, but it never checks the running total against
the sink buffer length on continuation segments. siw_check_sge() resolves
and validates the sink memory only on the first fragment (the if (!*mem)
branch), and siw_rresp_check_ntoh() compares the cumulative length against
wqe->bytes only on the final segment (the !frx->more_ddp_segs guard).
A connected siw peer that answers an outstanding RREAD with Read Response
segments that keep the DDP Last flag clear, carrying more total payload
than the RREAD requested, drives wqe->processed past the validated sink
buffer; the next siw_rx_data() call writes out of bounds at
sge->laddr + wqe->processed. siw runs iWARP over ordinary routable TCP,
so the peer is the remote end of an established RDMA connection and needs
no local privilege.
Bound every segment before placement, exactly as siw_proc_send() and
siw_proc_write() already do for their tagged and untagged paths, and
terminate the connection with a base-or-bounds DDP error when the
Read Response would overrun the sink buffer.
This is the second receive-path length fix for this file. A separate
change rejects an MPA FPDU length that underflows the per-fragment
remainder in the header decode; that guard does not cover this case,
because here each individual segment length is self-consistent and only
the accumulated placement offset overruns the buffer.
CVSS Score
9.8
EPSS Score
0.007
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
fuse: clear intr_entry in fuse_resend and fuse_remove_pending_req
When fuse_resend() moves a request from fpq->processing back to
fiq->pending, it sets FR_PENDING and clears FR_SENT but does not
remove the requests intr_entry from fiq->interrupts. If the
request had FR_INTERRUPTED set from a prior signal, intr_entry
remains dangling on fiq->interrupts. When the requesting task
then receives a fatal signal, fuse_remove_pending_req() sees
FR_PENDING=1, removes the request from fiq->pending and frees it
via the refcount path, also without cleaning intr_entry. The
stale intr_entry causes use-after-free when fuse_read_interrupt()
iterates fiq->interrupts:
- list_del_init(&req->intr_entry) -> UAF write on freed slab
- req->in.h.unique -> UAF read, data leaked to userspace
Remove intr_entry from fiq->interrupts in fuse_resend() for
interrupted requests before they are placed back on fiq->pending.
Add a WARN_ON if the intr_entry is not empty on request destruction.
CVSS Score
7.8
EPSS Score
0.002
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
fuse: re-lock request before returning from fuse_ref_folio()
fuse_ref_folio() unlocks the request but does not re-lock it before
returning. fuse_chan_abort() can end the request and the async end
callback (eg fuse_writepage_free()) can free the args while the
subsequent copy chain logic after fuse_ref_folio() accesses them,
leading to use-after-free issues.
Fix this by locking the request in fuse_ref_folio() before returning.
CVSS Score
7.8
EPSS Score
0.002
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
xfs: don't wrap around quota ids in dqiterate
LOLLM noticed that q_id is an unsigned 32-bit variable. If it happens
to be set to XFS_DQ_ID_MAX due to a filesystem that actually has a dquot
for ID_MAX, then this addition will truncate to zero and the iteration
starts over. Fix this by casting to u64.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
kernel/fork: clear PF_BLOCK_TS in copy_process()
PF_BLOCK_TS is only set in blk_time_get_ns() when current->plug is
non-NULL, and blk_finish_plug() clears it via __blk_flush_plug()
before NULLing the plug pointer. copy_process() breaks the
invariant by inheriting PF_BLOCK_TS from the parent while resetting
the child's plug to NULL.
Clear PF_BLOCK_TS alongside that assignment so callers can rely on
"PF_BLOCK_TS set implies current->plug != NULL" and dereference
current->plug unguarded.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-07-24
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