kernel/git/stable/linux.git/tools/perf/util/dso.c, branch master

perf dso: Replace assert with runtime check in dso__read_symbol()

2026-08-15T13:37:14+00:00

dso__read_symbol() asserts that len <= jited_prog_len, where len comes from sym->end - sym->start (parsed from PERF_RECORD_KSYMBOL in perf.data). Both values originate from untrusted file input. With NDEBUG (production builds), the assert is compiled out, allowing an out-of-bounds heap read when the BPF program buffer is accessed. Without NDEBUG, a crafted perf.data crashes perf with an assertion failure. Replace the assert with a runtime bounds check that returns NULL with an appropriate error code, matching the existing error handling pattern in this function. Fixes: aa04707f507e ("perf dso: Support BPF programs in dso__read_symbol()") Reported-by: sashiko-bot Reviewed-by: Ian Rogers Cc: Song Liu Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Namhyung Kim

perf dso: Guard against cache underflow on short reads in dso_cache__memcpy()

2026-08-15T13:37:09+00:00

dso_cache__memcpy() computes cache_offset = offset - cache->offset, then cache_size = min(cache->size - cache_offset, size). The RB tree lookup in __dso_cache__find() matches using the full DSO__DATA_CACHE_SIZE window, but cache->size reflects the actual pread return value from dso_cache__populate(). A short pread (e.g. near end-of-file) makes cache->size smaller than DSO__DATA_CACHE_SIZE. If a subsequent access targets an offset past cache->offset + cache->size but within the DSO__DATA_CACHE_SIZE window, the cache entry is found but cache_offset exceeds cache->size. Since both are u64, the subtraction cache->size - cache_offset wraps to a large value, min() selects the caller's size, and memcpy reads out of bounds. Return 0 for an offset past the valid cached data. For a regular file a short pread only happens at end-of-file, so 0 is what a direct pread() at that offset would return: cached_io() stops its read loop as on EOF. Re-reading from the backing file would not help — a second pread at the same offset returns the same short count. Fixes: 366df72657e0 ("perf dso: Refactor dso_cache__read()") Reported-by: sashiko-bot Reviewed-by: Ian Rogers Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Namhyung Kim

perf dso: Use stored fd error instead of stale errno in file_read() and file_size()

2026-08-15T13:37:04+00:00

file_read() and file_size() use ret = -errno when dso__data(dso)->fd is negative after try_to_open_dso() fails. By this point errno has been through mutex_lock(), nsinfo__mountns_enter(), and multiple open() attempts inside try_to_open_dso() — it no longer reflects the actual open failure. If errno happens to be 0, ret = 0 looks like EOF rather than an error, and file_size() callers like dso__data_size() would then report a zero-sized file instead of failing. dso__data(dso)->fd is always negative on failure — -errno from __open_dso() when no filename could be built (e.g. -EINVAL, -ENOENT), or -1 when do_open() itself failed — and never 0, so use it directly instead of reading the stale global errno. No assert() or comment is needed after the assignment: the enclosing if (dso__data(dso)->fd < 0) already guarantees ret < 0 [Namhyung Kim review]. Fixes: 33bdedcea2d7 ("perf tools: Protect dso cache fd with a mutex") Reported-by: sashiko-bot Reviewed-by: Ian Rogers Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Namhyung Kim

perf dso: Guard close() against invalid fd in dso__decompress_kmodule_path()

2026-08-15T13:37:00+00:00

dso__decompress_kmodule_path() unconditionally calls close(fd) on the return value of decompress_kmodule(). When decompression fails or the DSO is not compressed, decompress_kmodule() returns -1. close(-1) fails with EBADF and clobbers errno, which callers up the chain (dso__get_filename → __open_dso) depend on for error propagation. Guard the close() call with fd >= 0 so only valid file descriptors are closed. Fixes: 42b3fa670825 ("perf tools: Introduce dso__decompress_kmodule_{fd,path}") Reported-by: sashiko-bot Reviewed-by: Ian Rogers Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Namhyung Kim

perf dso: Guard against errno==0 when dso__get_filename() returns NULL

2026-08-15T13:36:55+00:00

__open_dso() computes fd = -errno when dso__get_filename() returns NULL. Some failure paths in dso__get_filename() (e.g. binary type mismatch) return NULL without making a syscall, leaving errno at 0 from a prior successful call. fd = -0 = 0, which is stdin — subsequent code treats it as a valid file descriptor. Fall back to ENOENT when errno is 0, ensuring fd is always negative on failure. The forced ENOENT stays in errno for the callers that check it after a negative fd. It must not misdirect the try_to_open_dso() fallback loop, though: dso__get_filename()'s chroot fallback used to accept a stale ENOENT even when stat() succeeded on a non-regular file (e.g. a directory). Re-stat() there and only take the chroot path when stat() actually failed with ENOENT [sashiko-bot review of PATCH 1/5]. Fixes: eba5102d2f0b ("perf tools: Add global list of opened dso objects") Reported-by: sashiko-bot Reviewed-by: Ian Rogers Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Namhyung Kim

perf dso: Set standard errno on decompression failure

2026-06-17T12:21:03+00:00

dso__get_filename() sets errno to a negative custom DSO_LOAD_ERRNO value when kernel module decompression fails: errno = *dso__load_errno(dso); /* e.g. -9996 */ The caller __open_dso() then computes fd = -errno, producing a large positive value (9996) that looks like a valid file descriptor. This can cause close_data_fd() to close an unrelated fd used by another subsystem. Set errno to EIO instead. The detailed error code is already stored in dso__load_errno(dso) for diagnostic messages. Fixes: 1d6b3c9ba756a513 ("perf tools: Decompress kernel module when reading DSO data") Reported-by: sashiko-bot Cc: Namhyung Kim Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo

perf bpf: Validate array presence before casting BPF prog info pointers

2026-06-17T12:21:03+00:00

Several functions cast bpf_prog_info fields (jited_ksyms, jited_func_lens, jited_prog_insns) from u64 to pointers and dereference them. These fields are only valid pointers if bpil_offs_to_addr() converted their file offsets to addresses, which only happens when the corresponding PERF_BPIL_* bits are set in info_linear->arrays. A crafted perf.data can leave these bits unset while setting non-zero counts and offset values, causing the functions to dereference raw file offsets as pointers. Add array bitmask validation to all perf.data processing paths: - __bpf_event__print_bpf_prog_info(): check JITED_KSYMS and JITED_FUNC_LENS (changed to take struct perf_bpil *) - machine__process_bpf_event_load(): check JITED_KSYMS - bpf_read(): check JITED_INSNS before memcpy from jited_prog_insns - dso__disassemble_filename(): check JITED_INSNS before returning jited_prog_insns pointer Fixes: f8dfeae009effc0b ("perf bpf: Show more BPF program info in print_bpf_prog_info()") Reported-by: sashiko-bot Cc: Song Liu Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo

perf dso: Set error code when open() fails on uncompressed fallback path

2026-06-17T11:28:40+00:00

filename__decompress() has an early return for files that are not actually compressed, where it calls open() directly. When open() fails, the function returns -1 but never sets *err. The caller chain (decompress_kmodule → dso__decompress_kmodule_path → dso__get_filename) then reads *dso__load_errno(dso) to set errno, but that field was never populated, so errno gets a stale or zero value. With errno=0, __open_dso() computes fd = -errno = 0, which is non- negative, so callers treat fd 0 (stdin) as a valid DSO file descriptor. Set *err = errno when open() fails on the uncompressed path, matching the error handling on the compressed path at line 354. Reported-by: sashiko-bot Fixes: 8b42b7e5e8b5692b ("perf tools: Add is_compressed callback to compressions array") Cc: Jiri Olsa Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo

perf dso: Fix heap overflow in dso__get_filename() on decompressed path

2026-06-17T11:28:37+00:00

dso__get_filename() allocates name with malloc(PATH_MAX), but the dso__filename_with_chroot() path replaces name with an asprintf'd exact-size string (e.g. 8 bytes for "/a/b.ko"). When the DSO needs decompression, dso__decompress_kmodule_path() writes the temp path ("/tmp/perf-kmod-XXXXXX", 22 bytes) into newpath, and strcpy(name, newpath) overflows the smaller allocation. Replace the strcpy with strdup(newpath) + free(name) so the buffer is always correctly sized for its content. Reported-by: sashiko-bot Fixes: 1d6b3c9ba756a513 ("perf tools: Decompress kernel module when reading DSO data") Reviewed-by: Ian Rogers Cc: Namhyung Kim Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Use snprintf() in dso__read_running_kernel_build_id()

2026-06-10T21:56:01+00:00

dso__read_running_kernel_build_id() uses sprintf() to format a sysfs path from machine->root_dir into a PATH_MAX buffer. If root_dir is close to PATH_MAX in length, appending "/sys/kernel/notes" (18 bytes) overflows the stack buffer. Switch to snprintf() with sizeof(path) to prevent the overflow. Reported-by: sashiko-bot Fixes: cdd059d731eeb466 ("perf tools: Move dso_* related functions into dso object") Cc: Jiri Olsa Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo