From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- lib/checksum.c | 164 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 164 insertions(+) create mode 100644 lib/checksum.c (limited to 'lib/checksum.c') diff --git a/lib/checksum.c b/lib/checksum.c new file mode 100644 index 000000000..025ba546e --- /dev/null +++ b/lib/checksum.c @@ -0,0 +1,164 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * + * INET An implementation of the TCP/IP protocol suite for the LINUX + * operating system. INET is implemented using the BSD Socket + * interface as the means of communication with the user level. + * + * IP/TCP/UDP checksumming routines + * + * Authors: Jorge Cwik, + * Arnt Gulbrandsen, + * Tom May, + * Andreas Schwab, + * Lots of code moved from tcp.c and ip.c; see those files + * for more names. + * + * 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek: + * Fixed some nasty bugs, causing some horrible crashes. + * A: At some points, the sum (%0) was used as + * length-counter instead of the length counter + * (%1). Thanks to Roman Hodek for pointing this out. + * B: GCC seems to mess up if one uses too many + * data-registers to hold input values and one tries to + * specify d0 and d1 as scratch registers. Letting gcc + * choose these registers itself solves the problem. + */ + +/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access + kills, so most of the assembly has to go. */ + +#include +#include + +#include + +#ifndef do_csum +static unsigned int do_csum(const unsigned char *buff, int len) +{ + int odd; + unsigned int result = 0; + + if (len <= 0) + goto out; + odd = 1 & (unsigned long) buff; + if (odd) { +#ifdef __LITTLE_ENDIAN + result += (*buff << 8); +#else + result = *buff; +#endif + len--; + buff++; + } + if (len >= 2) { + if (2 & (unsigned long) buff) { + result += *(unsigned short *) buff; + len -= 2; + buff += 2; + } + if (len >= 4) { + const unsigned char *end = buff + ((unsigned)len & ~3); + unsigned int carry = 0; + do { + unsigned int w = *(unsigned int *) buff; + buff += 4; + result += carry; + result += w; + carry = (w > result); + } while (buff < end); + result += carry; + result = (result & 0xffff) + (result >> 16); + } + if (len & 2) { + result += *(unsigned short *) buff; + buff += 2; + } + } + if (len & 1) +#ifdef __LITTLE_ENDIAN + result += *buff; +#else + result += (*buff << 8); +#endif + result = csum_from32to16(result); + if (odd) + result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); +out: + return result; +} +#endif + +#ifndef ip_fast_csum +/* + * This is a version of ip_compute_csum() optimized for IP headers, + * which always checksum on 4 octet boundaries. + */ +__sum16 ip_fast_csum(const void *iph, unsigned int ihl) +{ + return (__force __sum16)~do_csum(iph, ihl*4); +} +EXPORT_SYMBOL(ip_fast_csum); +#endif + +/* + * computes the checksum of a memory block at buff, length len, + * and adds in "sum" (32-bit) + * + * returns a 32-bit number suitable for feeding into itself + * or csum_tcpudp_magic + * + * this function must be called with even lengths, except + * for the last fragment, which may be odd + * + * it's best to have buff aligned on a 32-bit boundary + */ +__wsum csum_partial(const void *buff, int len, __wsum wsum) +{ + unsigned int sum = (__force unsigned int)wsum; + unsigned int result = do_csum(buff, len); + + /* add in old sum, and carry.. */ + result += sum; + if (sum > result) + result += 1; + return (__force __wsum)result; +} +EXPORT_SYMBOL(csum_partial); + +/* + * this routine is used for miscellaneous IP-like checksums, mainly + * in icmp.c + */ +__sum16 ip_compute_csum(const void *buff, int len) +{ + return (__force __sum16)~do_csum(buff, len); +} +EXPORT_SYMBOL(ip_compute_csum); + +#ifndef csum_tcpudp_nofold +static inline u32 from64to32(u64 x) +{ + /* add up 32-bit and 32-bit for 32+c bit */ + x = (x & 0xffffffff) + (x >> 32); + /* add up carry.. */ + x = (x & 0xffffffff) + (x >> 32); + return (u32)x; +} + +__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, + __u32 len, __u8 proto, __wsum sum) +{ + unsigned long long s = (__force u32)sum; + + s += (__force u32)saddr; + s += (__force u32)daddr; +#ifdef __BIG_ENDIAN + s += proto + len; +#else + s += (proto + len) << 8; +#endif + return (__force __wsum)from64to32(s); +} +EXPORT_SYMBOL(csum_tcpudp_nofold); +#endif -- cgit v1.3.1