diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-19 10:09:22 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-19 10:09:22 -0700 |
| commit | f4cdf7ca9a1fdcca413157df19753f388a5a224e (patch) | |
| tree | 60a31895b2446cd7fa27514e8c2843534a0de0da /lib/strnlen_user.c | |
| download | linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.tar.gz linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.zip | |
Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted
Pull media updates from Mauro Carvalho Chehab:
- v4l2-core: added ISP statistics support and per-block validation
- v4l2-core: Allow unknown HDR10 white point and luminance
- New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor
- New codec: Milos: VPU v2.0 codec support
- isp driver: gained support for Dreamchip RPPX1 ISP framework
- vsp1 driver: gained support for RZ/T2H and RZ/N2H
- Novalake driver: gained CVS support for new NVL hardware
- dvb-core: fix feed leak on failed DMX_ADD_PID
- several driver fixes, cleanups and minor improvements
* tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits)
media: ipu-bridge: check all DMI entries when overriding sensor rotation
media: v4l2-async: avoid deleting unlinked ASC entry on link error
media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement
media: intel/ipu6: fix async notifier cleanup leak on parse error
media: staging/ipu7: fix async notifier UAF on probe error path
media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path
media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem()
media: rcar-isp: Fix VSPX reference leaks
media: rcar-isp: Release ISPCORE resources
media: i2c: imx415: Release runtime PM reference on VBLANK error
media: i2c: imx415: Return test pattern write errors
media: renesas: vsp1: Declare index variables in for loop statement
media: renesas: vsp1: Make reset control optional to support platforms without a reset line
media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs
media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs
media: nxp: imx8-isi: Add additional 32-bit RGB format support
media: nxp: imx8-isi: Add 16-bit raw Bayer format support
media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams
media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks
media: nxp: imx8-isi: Correct color map between V4L2 and ISI
...
Diffstat (limited to 'lib/strnlen_user.c')
| -rw-r--r-- | lib/strnlen_user.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c new file mode 100644 index 000000000..4a6574b67 --- /dev/null +++ b/lib/strnlen_user.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/kernel.h> +#include <linux/export.h> +#include <linux/uaccess.h> +#include <linux/mm.h> +#include <linux/bitops.h> + +#include <asm/word-at-a-time.h> + +/* + * Do a strnlen, return length of string *with* final '\0'. + * 'count' is the user-supplied count, while 'max' is the + * address space maximum. + * + * Return 0 for exceptions (which includes hitting the address + * space maximum), or 'count+1' if hitting the user-supplied + * maximum count. + * + * NOTE! We can sometimes overshoot the user-supplied maximum + * if it fits in a aligned 'long'. The caller needs to check + * the return value against "> max". + */ +static __always_inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max) +{ + const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; + unsigned long align, res = 0; + unsigned long c; + + /* + * Do everything aligned. But that means that we + * need to also expand the maximum.. + */ + align = (sizeof(unsigned long) - 1) & (unsigned long)src; + src -= align; + max += align; + + unsafe_get_user(c, (unsigned long __user *)src, efault); + c |= aligned_byte_mask(align); + + for (;;) { + unsigned long data; + if (has_zero(c, &data, &constants)) { + data = prep_zero_mask(c, data, &constants); + data = create_zero_mask(data); + return res + find_zero(data) + 1 - align; + } + res += sizeof(unsigned long); + /* We already handled 'unsigned long' bytes. Did we do it all ? */ + if (unlikely(max <= sizeof(unsigned long))) + break; + max -= sizeof(unsigned long); + unsafe_get_user(c, (unsigned long __user *)(src+res), efault); + } + res -= align; + + /* + * Uhhuh. We hit 'max'. But was that the user-specified maximum + * too? If so, return the marker for "too long". + */ + if (res >= count) + return count+1; + + /* + * Nope: we hit the address space limit, and we still had more + * characters the caller would have wanted. That's 0. + */ +efault: + return 0; +} + +/** + * strnlen_user: - Get the size of a user string INCLUDING final NUL. + * @str: The string to measure. + * @count: Maximum count (including NUL character) + * + * Context: User context only. This function may sleep if pagefaults are + * enabled. + * + * Get the size of a NUL-terminated string in user space. + * + * Returns the size of the string INCLUDING the terminating NUL. + * If the string is too long, returns a number larger than @count. User + * has to check the return value against "> count". + * On exception (or invalid count), returns 0. + * + * NOTE! You should basically never use this function. There is + * almost never any valid case for using the length of a user space + * string, since the string can be changed at any time by other + * threads. Use "strncpy_from_user()" instead to get a stable copy + * of the string. + */ +long strnlen_user(const char __user *str, long count) +{ + unsigned long max_addr, src_addr; + + if (unlikely(count <= 0)) + return 0; + + if (can_do_masked_user_access()) { + long retval; + + str = masked_user_read_access_begin(str); + retval = do_strnlen_user(str, count, count); + user_read_access_end(); + return retval; + } + + max_addr = TASK_SIZE_MAX; + src_addr = (unsigned long)untagged_addr(str); + if (likely(src_addr < max_addr)) { + unsigned long max = max_addr - src_addr; + long retval; + + /* + * Truncate 'max' to the user-specified limit, so that + * we only have one limit we need to check in the loop + */ + if (max > count) + max = count; + + if (user_read_access_begin(str, max)) { + retval = do_strnlen_user(str, count, max); + user_read_access_end(); + return retval; + } + } + return 0; +} +EXPORT_SYMBOL(strnlen_user); |
