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 --- scripts/elf-parse.c | 198 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 198 insertions(+) create mode 100644 scripts/elf-parse.c (limited to 'scripts/elf-parse.c') diff --git a/scripts/elf-parse.c b/scripts/elf-parse.c new file mode 100644 index 000000000..99869ff91 --- /dev/null +++ b/scripts/elf-parse.c @@ -0,0 +1,198 @@ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "elf-parse.h" + +struct elf_funcs elf_parser; + +/* + * Get the whole file as a programming convenience in order to avoid + * malloc+lseek+read+free of many pieces. If successful, then mmap + * avoids copying unused pieces; else just read the whole file. + * Open for both read and write. + */ +static void *map_file(char const *fname, size_t *size) +{ + int fd; + struct stat sb; + void *addr = NULL; + + fd = open(fname, O_RDWR); + if (fd < 0) { + perror(fname); + return NULL; + } + if (fstat(fd, &sb) < 0) { + perror(fname); + goto out; + } + if (!S_ISREG(sb.st_mode)) { + fprintf(stderr, "not a regular file: %s\n", fname); + goto out; + } + + addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); + if (addr == MAP_FAILED) { + fprintf(stderr, "Could not mmap file: %s\n", fname); + goto out; + } + + *size = sb.st_size; + +out: + close(fd); + return addr; +} + +static int elf_parse(const char *fname, void *addr, uint32_t types) +{ + Elf_Ehdr *ehdr = addr; + uint16_t type; + + switch (ehdr->e32.e_ident[EI_DATA]) { + case ELFDATA2LSB: + elf_parser.r = rle; + elf_parser.r2 = r2le; + elf_parser.r8 = r8le; + elf_parser.w = wle; + elf_parser.w8 = w8le; + break; + case ELFDATA2MSB: + elf_parser.r = rbe; + elf_parser.r2 = r2be; + elf_parser.r8 = r8be; + elf_parser.w = wbe; + elf_parser.w8 = w8be; + break; + default: + fprintf(stderr, "unrecognized ELF data encoding %d: %s\n", + ehdr->e32.e_ident[EI_DATA], fname); + return -1; + } + + if (memcmp(ELFMAG, ehdr->e32.e_ident, SELFMAG) != 0 || + ehdr->e32.e_ident[EI_VERSION] != EV_CURRENT) { + fprintf(stderr, "unrecognized ELF file %s\n", fname); + return -1; + } + + type = elf_parser.r2(&ehdr->e32.e_type); + if (!((1 << type) & types)) { + fprintf(stderr, "Invalid ELF type file %s\n", fname); + return -1; + } + + switch (ehdr->e32.e_ident[EI_CLASS]) { + case ELFCLASS32: { + elf_parser.ehdr_shoff = ehdr32_shoff; + elf_parser.ehdr_shentsize = ehdr32_shentsize; + elf_parser.ehdr_shstrndx = ehdr32_shstrndx; + elf_parser.ehdr_shnum = ehdr32_shnum; + elf_parser.shdr_addr = shdr32_addr; + elf_parser.shdr_offset = shdr32_offset; + elf_parser.shdr_link = shdr32_link; + elf_parser.shdr_size = shdr32_size; + elf_parser.shdr_name = shdr32_name; + elf_parser.shdr_type = shdr32_type; + elf_parser.shdr_entsize = shdr32_entsize; + elf_parser.sym_type = sym32_type; + elf_parser.sym_name = sym32_name; + elf_parser.sym_value = sym32_value; + elf_parser.sym_shndx = sym32_shndx; + elf_parser.rela_offset = rela32_offset; + elf_parser.rela_info = rela32_info; + elf_parser.rela_addend = rela32_addend; + elf_parser.rela_write_addend = rela32_write_addend; + + if (elf_parser.r2(&ehdr->e32.e_ehsize) != sizeof(Elf32_Ehdr) || + elf_parser.r2(&ehdr->e32.e_shentsize) != sizeof(Elf32_Shdr)) { + fprintf(stderr, + "unrecognized ET_EXEC/ET_DYN file: %s\n", fname); + return -1; + } + + } + break; + case ELFCLASS64: { + elf_parser.ehdr_shoff = ehdr64_shoff; + elf_parser.ehdr_shentsize = ehdr64_shentsize; + elf_parser.ehdr_shstrndx = ehdr64_shstrndx; + elf_parser.ehdr_shnum = ehdr64_shnum; + elf_parser.shdr_addr = shdr64_addr; + elf_parser.shdr_offset = shdr64_offset; + elf_parser.shdr_link = shdr64_link; + elf_parser.shdr_size = shdr64_size; + elf_parser.shdr_name = shdr64_name; + elf_parser.shdr_type = shdr64_type; + elf_parser.shdr_entsize = shdr64_entsize; + elf_parser.sym_type = sym64_type; + elf_parser.sym_name = sym64_name; + elf_parser.sym_value = sym64_value; + elf_parser.sym_shndx = sym64_shndx; + elf_parser.rela_offset = rela64_offset; + elf_parser.rela_info = rela64_info; + elf_parser.rela_addend = rela64_addend; + elf_parser.rela_write_addend = rela64_write_addend; + + if (elf_parser.r2(&ehdr->e64.e_ehsize) != sizeof(Elf64_Ehdr) || + elf_parser.r2(&ehdr->e64.e_shentsize) != sizeof(Elf64_Shdr)) { + fprintf(stderr, + "unrecognized ET_EXEC/ET_DYN file: %s\n", + fname); + return -1; + } + + } + break; + default: + fprintf(stderr, "unrecognized ELF class %d %s\n", + ehdr->e32.e_ident[EI_CLASS], fname); + return -1; + } + return 0; +} + +int elf_map_machine(void *addr) +{ + Elf_Ehdr *ehdr = addr; + + return elf_parser.r2(&ehdr->e32.e_machine); +} + +int elf_map_long_size(void *addr) +{ + Elf_Ehdr *ehdr = addr; + + return ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8; +} + +void *elf_map(char const *fname, size_t *size, uint32_t types) +{ + void *addr; + int ret; + + addr = map_file(fname, size); + if (!addr) + return NULL; + + ret = elf_parse(fname, addr, types); + if (ret < 0) { + elf_unmap(addr, *size); + return NULL; + } + + return addr; +} + +void elf_unmap(void *addr, size_t size) +{ + munmap(addr, size); +} -- cgit v1.3.1