ImageMagick before 7.1.2-27 contains a memory leak vulnerability in the magick command-line interface when invalid options are provided. Attackers can trigger memory exhaustion by repeatedly supplying malformed command-line arguments to consume system resources.
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.
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.
In the Linux kernel, the following vulnerability has been resolved:
mm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access
The page_ext iteration API does not validate if the PFN still belongs to a
valid section while advancing the iterator. When dynamically adding
memory in the hotplug path, it can lead to a NULL pointer dereference
during page_ext_lookup at the boundary of the last valid section when
iterator count equals __pgcount.
The for_each_page_ext() macro calls page_ext_iter_next() as its loop
increment. for_each_page_ext() does a "__page_ext =
page_ext_iter_next(&__iter)" at the end. This causes page_ext_iter_next()
to increment iter->index past __pgcount and call page_ext_lookup(start_pfn
+ __pgcount). During memory hotplug (online), the PFN at start_pfn +
__pgcount may belong to a section that has not yet been initialized,
causing page_ext_lookup() to trigger a NULL pointer dereference.
[ 14.555124][ T846] Call trace:
[ 14.555125][ T846] lookup_page_ext+0x6c/0x108 (P)
[ 14.555127][ T846] page_ext_lookup+0x30/0x3c
[ 14.555129][ T846] __reset_page_owner+0x11c/0x260
[ 14.571201][ T846] __free_pages_ok+0x5e8/0x8e0
[ 14.571204][ T846] __free_pages_core+0x78/0xf0
[ 14.571206][ T846] generic_online_page+0x14/0x24
[ 14.597782][ T846] online_pages+0x178/0x30c
[ 14.597784][ T846] memory_block_change_state+0x284/0x32c
[ 14.597787][ T846] memory_subsys_online+0x4c/0x64
[ 14.597789][ T846] device_online+0x88/0xb0
[ 14.597791][ T846] online_memory_block+0x30/0x40
[ 14.597793][ T846] walk_memory_blocks+0xac/0xe8
[ 14.597794][ T846] add_memory_resource+0x280/0x298
[ 14.656161][ T846] add_memory+0x60/0x98
Move the iteration boundary enforcement inside the iterator functions, so
callers cannot inadvertently access beyond the requested range.
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.
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.]
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.
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits
Move the handling of fastpath userspace exits into vendor code to ensure
KVM runs vendor specific operations that need to run before userspace gains
control of the vCPU. E.g. for VMX (and soon to be for SVM as well), KVM
needs to flush the PML buffer prior to exiting to userspace, otherwise any
memory written by the final KVM_RUN might never be flagged as dirty.
Note, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in
general, as that risks consuming stale state in a fastpath handler. That
will be addressed in a future change.
In the Linux kernel, the following vulnerability has been resolved:
KVM: SEV: Pin source page for write when adding CPUID data for SNP guest
When populating a guest_memfd instance with the initial CPUID data for an
SNP guest, acquire a writable pin on the source page as KVM will write back
the "correct" CPUID information if the userspace provided data is rejected
by trusted firmware. Because KVM writes to the source page using a kernel
mapping, pinning for read could result in KVM clobbering read-only memory.
Note, well-behaved VMMs are unlikely to be affected, as CPUID information
is almost always dynamically generated by userspace, i.e. it's unlikely for
the CPUID information to be backed by a read-only mapping.
[sean: rewrite shortlog and changelog, tag for stable@]
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU
flush_hyp_vcpu() copies the host vCPU context into the hyp's private
vCPU on every run. ctxt_to_vcpu() expects a guest context to have a
NULL __hyp_running_vcpu, which is only ever set on the host context, so
that it resolves the vCPU via container_of(). While this is generally
the case, flush_hyp_vcpu() copies the context verbatim and does not
enforce this, so a value provided by the host is dereferenced at EL2
(host -> EL2).
Fix by clearing __hyp_running_vcpu after the copy.