kernel/linux.git/drivers/char/hw_random, branch v5.10.261

hwrng: virtio: clamp device-reported used.len at copy_data()

2026-07-24T13:48:49+00:00

commit e3046eeada299f917a8ad883af4434bfb86556b1 upstream. random_recv_done() stores the device-reported used.len directly into vi->data_avail. copy_data() then indexes vi->data[] using vi->data_idx (advanced by previous copy_data() calls) and issues a memcpy() without re-validating either value against the posted buffer size sizeof(vi->data) (SMP_CACHE_BYTES bytes, typically 32 or 64). A malicious or buggy virtio-rng backend can set used.len beyond sizeof(vi->data), steering the memcpy() past the end of the inline array into adjacent kmalloc-1k slab bytes. hwrng_fillfn() mixes those bytes into the guest RNG, and guest root can also observe them directly via /dev/hwrng. Concrete impact is inside the guest: - Memory-safety / hardening: any virtio-rng backend that over-reports used.len causes the driver to read past vi->data into unrelated slab contents. hwrng_fillfn() is a kernel thread that runs as soon as the device is probed; no guest userspace interaction is required to first-trigger the OOB. - Cross-boundary leak (confidential-compute threat model): a malicious hypervisor cooperating with a malicious or compromised guest root userspace can use /dev/hwrng as a leak channel for guest-kernel heap data. The host sets a large used.len, guest root reads /dev/hwrng, and the returned bytes contain guest kernel slab contents that were adjacent to vi->data. In practice, confidential-compute guests (SEV-SNP, TDX) usually disable virtio-rng entirely, so this path is narrow, but the fix is still worth carrying because the underlying memory-safety bug contaminates the guest RNG on any host. KASAN confirms the OOB on a 7.1-rc4 guest whose virtio-rng backend has been patched to report used.len = 0x10000: BUG: KASAN: slab-out-of-bounds in virtio_read+0x394/0x5d0 Read of size 64 at addr ffff88800ae0ba20 by task hwrng/52 Call Trace: __asan_memcpy+0x23/0x60 virtio_read+0x394/0x5d0 hwrng_fillfn+0xb2/0x470 kthread+0x2cc/0x3a0 Allocated by task 1: probe_common+0xa5/0x660 virtio_dev_probe+0x549/0xbc0 The buggy address belongs to the object at ffff88800ae0b800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 0 bytes to the right of allocated 544-byte region [ffff88800ae0b800, ffff88800ae0ba20) Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened usb9pfs_rx_complete() against unchecked device-reported length in the USB 9p transport. With the clamp at point of use and array_index_nospec() in place, the same harness boots cleanly: copy_data() returns zero for the bogus report, the device-supplied bytes after data_idx are discarded, and the driver issues a fresh request. Fixes: f7f510ec1957 ("virtio: An entropy device, as suggested by hpa.") Cc: stable@vger.kernel.org Suggested-by: Michael S. Tsirkin Signed-off-by: Michael Bommarito Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Michael S. Tsirkin Message-ID: <20260531142251.2792061-1-michael.bommarito@gmail.com> Signed-off-by: Greg Kroah-Hartman

hwrng: ks-sa - fix division by zero in ks_sa_rng_init

2025-10-29T13:01:07+00:00

[ Upstream commit 612b1dfeb414dfa780a6316014ceddf9a74ff5c0 ] Fix division by zero in ks_sa_rng_init caused by missing clock pointer initialization. The clk_get_rate() call is performed on an uninitialized clk pointer, resulting in division by zero when calculating delay values. Add clock initialization code before using the clock. Fixes: 6d01d8511dce ("hwrng: ks-sa - Add minimum sleep time before ready-polling") Signed-off-by: Nishanth Menon drivers/char/hw_random/ks-sa-rng.c | 7 +++++++ 1 file changed, 7 insertions(+) Reviewed-by: Alexander Sverdlin Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin

hwrng: mtk - handle devm_pm_runtime_enable errors

2025-08-28T14:22:34+00:00

[ Upstream commit 522a242a18adc5c63a24836715dbeec4dc3faee1 ] Although unlikely, devm_pm_runtime_enable() call might fail, so handle the return value. Fixes: 78cb66caa6ab ("hwrng: mtk - Use devm_pm_runtime_enable") Signed-off-by: Ovidiu Panait Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin

hwrng: cctrng - Add missing clk_disable_unprepare in cctrng_resume

2024-10-17T13:08:02+00:00

commit 4b7acc85de14ee8a2236f54445dc635d47eceac0 upstream. Add the missing clk_disable_unprepare() before return in cctrng_resume(). Fixes: a583ed310bb6 ("hwrng: cctrng - introduce Arm CryptoCell driver") Cc: Signed-off-by: Gaosheng Cui Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

hwrng: mtk - Use devm_pm_runtime_enable

2024-10-17T13:08:02+00:00

commit 78cb66caa6ab5385ac2090f1aae5f3c19e08f522 upstream. Replace pm_runtime_enable with the devres-enabled version which can trigger pm_runtime_disable. Otherwise, the below appears during reload driver. mtk_rng 1020f000.rng: Unbalanced pm_runtime_enable! Fixes: 81d2b34508c6 ("hwrng: mtk - add runtime PM support") Cc: Suggested-by: Chen-Yu Tsai Signed-off-by: Guoqing Jiang Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

hwrng: amd - Convert PCIBIOS_* return codes to errnos

2024-08-19T03:40:58+00:00

commit 14cba6ace79627a57fb9058582b03f0ed3832390 upstream. amd_rng_mod_init() uses pci_read_config_dword() that returns PCIBIOS_* codes. The return code is then returned as is but amd_rng_mod_init() is a module_init() function that should return normal errnos. Convert PCIBIOS_* returns code using pcibios_err_to_errno() into normal errno before returning it. Fixes: 96d63c0297cc ("[PATCH] Add AMD HW RNG driver") Cc: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

hwrng: core - Fix page fault dead lock on mmap-ed hwrng

2024-02-23T07:41:52+00:00

commit 78aafb3884f6bc6636efcc1760c891c8500b9922 upstream. There is a dead-lock in the hwrng device read path. This triggers when the user reads from /dev/hwrng into memory also mmap-ed from /dev/hwrng. The resulting page fault triggers a recursive read which then dead-locks. Fix this by using a stack buffer when calling copy_to_user. Reported-by: Edward Adam Davis Reported-by: syzbot+c52ab18308964d248092@syzkaller.appspotmail.com Fixes: 9996508b3353 ("hwrng: core - Replace u32 in driver API with byte array") Cc: Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

hwrng: geode - fix accessing registers

2023-11-20T10:06:50+00:00

[ Upstream commit 464bd8ec2f06707f3773676a1bd2c64832a3c805 ] When the membase and pci_dev pointer were moved to a new struct in priv, the actual membase users were left untouched, and they started reading out arbitrary memory behind the struct instead of registers. This unfortunately turned the RNG into a constant number generator, depending on the content of what was at that offset. To fix this, update geode_rng_data_{read,present}() to also get the membase via amd_geode_priv, and properly read from the right addresses again. Fixes: 9f6ec8dc574e ("hwrng: geode - Fix PCI device refcount leak") Reported-by: Timur I. Davletshin Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217882 Tested-by: Timur I. Davletshin Suggested-by: Jo-Philipp Wich Signed-off-by: Jonas Gorski Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin

hwrng: iproc-rng200 - Implement suspend and resume calls

2023-09-19T10:20:09+00:00

[ Upstream commit 8e03dd62e5be811efbf0cbeba47e79e793519105 ] Chips such as BCM7278 support system wide suspend/resume which will cause the HWRNG block to lose its state and reset to its power on reset register values. We need to cleanup and re-initialize the HWRNG for it to be functional coming out of a system suspend cycle. Fixes: c3577f6100ca ("hwrng: iproc-rng200 - Add support for BCM7278") Signed-off-by: Florian Fainelli Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin

hwrng: nomadik - keep clock enabled while hwrng is registered

2023-09-19T10:20:08+00:00

[ Upstream commit 039980de89dc9dd757418d6f296e4126cc3f86c3 ] The nomadik driver uses devres to register itself with the hwrng core, the driver will be unregistered from hwrng when its device goes out of scope. This happens after the driver's remove function is called. However, nomadik's clock is disabled in the remove function. There's a short timeframe where nomadik is still registered with the hwrng core although its clock is disabled. I suppose the clock must be active to access the hardware and serve requests from the hwrng core. Switch to devm_clk_get_enabled and let devres disable the clock and unregister the hwrng. This avoids the race condition. Fixes: 3e75241be808 ("hwrng: drivers - Use device-managed registration API") Signed-off-by: Martin Kaiser Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin