kernel/linux.git/drivers/char/hw_random, branch v6.1.186

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

2026-07-24T13:54:21+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

2025-10-15T09:56:38+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: nomadik - add ARM_AMBA dependency

2025-10-15T09:56:30+00:00

[ Upstream commit efaa2d815a0e4d1c06750e587100f6f7f4ee5497 ] Compile-testing this driver is only possible when the AMBA bus driver is available in the kernel: x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_remove': nomadik-rng.c:(.text+0x67): undefined reference to `amba_release_regions' x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_probe': nomadik-rng.c:(.text+0xee): undefined reference to `amba_request_regions' x86_64-linux-ld: nomadik-rng.c:(.text+0x18d): undefined reference to `amba_release_regions' The was previously implied by the 'depends on ARCH_NOMADIK', but needs to be specified for the COMPILE_TEST case. Fixes: d5e93b3374e4 ("hwrng: Kconfig - Add helper dependency on COMPILE_TEST") Signed-off-by: Arnd Bergmann Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin

hwrng: mtk - handle devm_pm_runtime_enable errors

2025-08-15T10:05:03+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

2024-10-17T13:21:23+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: bcm2835 - Add missing clk_disable_unprepare in bcm2835_rng_init

2024-10-17T13:21:22+00:00

commit d57e2f7cffd57fe2800332dec768ec1b67a4159f upstream. Add the missing clk_disable_unprepare() before return in bcm2835_rng_init(). Fixes: e5f9f41d5e62 ("hwrng: bcm2835 - add reset support") Cc: Signed-off-by: Gaosheng Cui Reviewed-by: Florian Fainelli Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

hwrng: mtk - Use devm_pm_runtime_enable

2024-10-17T13:21:22+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

2024-08-03T06:49:36+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

2024-02-01T00:16:58+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

2023-11-20T10:52:04+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