Linux: >> Linux Kernel >> 3.0.95 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
vfs: fix race between evice_inodes() and find_inode()&iput()
Hi, all
Recently I noticed a bug[1] in btrfs, after digged it into
and I believe it'a race in vfs.
Let's assume there's a inode (ie ino 261) with i_count 1 is
called by iput(), and there's a concurrent thread calling
generic_shutdown_super().
cpu0: cpu1:
iput() // i_count is 1
->spin_lock(inode)
->dec i_count to 0
->iput_final() generic_shutdown_super()
->__inode_add_lru() ->evict_inodes()
// cause some reason[2] ->if (atomic_read(inode->i_count)) continue;
// return before // inode 261 passed the above check
// list_lru_add_obj() // and then schedule out
->spin_unlock()
// note here: the inode 261
// was still at sb list and hash list,
// and I_FREEING|I_WILL_FREE was not been set
btrfs_iget()
// after some function calls
->find_inode()
// found the above inode 261
->spin_lock(inode)
// check I_FREEING|I_WILL_FREE
// and passed
->__iget()
->spin_unlock(inode) // schedule back
->spin_lock(inode)
// check (I_NEW|I_FREEING|I_WILL_FREE) flags,
// passed and set I_FREEING
iput() ->spin_unlock(inode)
->spin_lock(inode) ->evict()
// dec i_count to 0
->iput_final()
->spin_unlock()
->evict()
Now, we have two threads simultaneously evicting
the same inode, which may trigger the BUG(inode->i_state & I_CLEAR)
statement both within clear_inode() and iput().
To fix the bug, recheck the inode->i_count after holding i_lock.
Because in the most scenarios, the first check is valid, and
the overhead of spin_lock() can be reduced.
If there is any misunderstanding, please let me know, thanks.
[1]: https://lore.kernel.org/linux-btrfs/000000000000eabe1d0619c48986@google.com/
[2]: The reason might be 1. SB_ACTIVE was removed or 2. mapping_shrinkable()
return false when I reproduced the bug.
CVSS Score
4.7
EPSS Score
0.0
Published
2024-10-21
In the Linux kernel, the following vulnerability has been resolved:
mm: avoid leaving partial pfn mappings around in error case
As Jann points out, PFN mappings are special, because unlike normal
memory mappings, there is no lifetime information associated with the
mapping - it is just a raw mapping of PFNs with no reference counting of
a 'struct page'.
That's all very much intentional, but it does mean that it's easy to
mess up the cleanup in case of errors. Yes, a failed mmap() will always
eventually clean up any partial mappings, but without any explicit
lifetime in the page table mapping itself, it's very easy to do the
error handling in the wrong order.
In particular, it's easy to mistakenly free the physical backing store
before the page tables are actually cleaned up and (temporarily) have
stale dangling PTE entries.
To make this situation less error-prone, just make sure that any partial
pfn mapping is torn down early, before any other error handling.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-10-15
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Avoid overflow from uint32_t to uint8_t
[WHAT & HOW]
dmub_rb_cmd's ramping_boundary has size of uint8_t and it is assigned
0xFFFF. Fix it by changing it to uint8_t with value of 0xFF.
This fixes 2 INTEGER_OVERFLOW issues reported by Coverity.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-10-09
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Remove register from DCN35 DMCUB diagnostic collection
[Why]
These registers should not be read from driver and triggering the
security violation when DMCUB work times out and diagnostics are
collected blocks Z8 entry.
[How]
Remove the register read from DCN35.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-10-09
In the Linux kernel, the following vulnerability has been resolved:
staging: iio: frequency: ad9834: Validate frequency parameter value
In ad9834_write_frequency() clk_get_rate() can return 0. In such case
ad9834_calc_freqreg() call will lead to division by zero. Checking
'if (fout > (clk_freq / 2))' doesn't protect in case of 'fout' is 0.
ad9834_write_frequency() is called from ad9834_write(), where fout is
taken from text buffer, which can contain any value.
Modify parameters checking.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-10-09
In the Linux kernel, the following vulnerability has been resolved:
spi: hisi-kunpeng: Add verification for the max_frequency provided by the firmware
If the value of max_speed_hz is 0, it may cause a division by zero
error in hisi_calc_effective_speed().
The value of max_speed_hz is provided by firmware.
Firmware is generally considered as a trusted domain. However, as
division by zero errors can cause system failure, for defense measure,
the value of max_speed is validated here. So 0 is regarded as invalid
and an error code is returned.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-10-09
In the Linux kernel, the following vulnerability has been resolved:
i3c: mipi-i3c-hci: Error out instead on BUG_ON() in IBI DMA setup
Definitely condition dma_get_cache_alignment * defined value > 256
during driver initialization is not reason to BUG_ON(). Turn that to
graceful error out with -EINVAL.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-10-09
In the Linux kernel, the following vulnerability has been resolved:
scsi: pm80xx: Set phy->enable_completion only when we wait for it
pm8001_phy_control() populates the enable_completion pointer with a stack
address, sends a PHY_LINK_RESET / PHY_HARD_RESET, waits 300 ms, and
returns. The problem arises when a phy control response comes late. After
300 ms the pm8001_phy_control() function returns and the passed
enable_completion stack address is no longer valid. Late phy control
response invokes complete() on a dangling enable_completion pointer which
leads to a kernel crash.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-10-09
In the Linux kernel, the following vulnerability has been resolved:
PCI: keystone: Add workaround for Errata #i2037 (AM65x SR 1.0)
Errata #i2037 in AM65x/DRA80xM Processors Silicon Revision 1.0
(SPRZ452D_July 2018_Revised December 2019 [1]) mentions when an
inbound PCIe TLP spans more than two internal AXI 128-byte bursts,
the bus may corrupt the packet payload and the corrupt data may
cause associated applications or the processor to hang.
The workaround for Errata #i2037 is to limit the maximum read
request size and maximum payload size to 128 bytes. Add workaround
for Errata #i2037 here.
The errata and workaround is applicable only to AM65x SR 1.0 and
later versions of the silicon will have this fixed.
[1] -> https://www.ti.com/lit/er/sprz452i/sprz452i.pdf
CVSS Score
5.5
EPSS Score
0.0
Published
2024-10-09
In the Linux kernel, the following vulnerability has been resolved:
lib/generic-radix-tree.c: Fix rare race in __genradix_ptr_alloc()
If we need to increase the tree depth, allocate a new node, and then
race with another thread that increased the tree depth before us, we'll
still have a preallocated node that might be used later.
If we then use that node for a new non-root node, it'll still have a
pointer to the old root instead of being zeroed - fix this by zeroing it
in the cmpxchg failure path.
CVSS Score
4.7
EPSS Score
0.0
Published
2024-10-09