strcpy() is deprecated and its behavior is undefined when the source and destination buffers overlap. Use memmove() instead to avoid any undefined behavior.
Adjust comments for clarity. Link: https://github.com/KSPP/linux/issues/88 Signed-off-by: Thorsten Blum <thorsten.b...@linux.dev> --- Changes in v2: - Use memmove() because of strcpy()'s undefined behavior with overlapping buffers as suggested by Doug Anderson - Compile-tested only - Link to v1: https://lore.kernel.org/lkml/20250811170351.68985-1-thorsten.b...@linux.dev/ --- kernel/debug/kdb/kdb_io.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c index 9b11b10b120c..b12b9db75c1d 100644 --- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -714,8 +714,8 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap) * it, depending on the results of the search. */ cp++; /* to byte after the newline */ - replaced_byte = *cp; /* remember what/where it was */ - cphold = cp; + replaced_byte = *cp; /* remember what it was */ + cphold = cp; /* remember where it was */ *cp = '\0'; /* end the string for our search */ /* @@ -732,8 +732,9 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap) * Shift the buffer left. */ *cphold = replaced_byte; - strcpy(kdb_buffer, cphold); - len = strlen(kdb_buffer); + len = strlen(cphold); + /* Use memmove() because the buffers overlap */ + memmove(kdb_buffer, cphold, len + 1); next_avail = kdb_buffer + len; size_avail = sizeof(kdb_buffer) - len; goto kdb_print_out; @@ -872,8 +873,9 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap) */ if (kdb_grepping_flag && !suspend_grep) { *cphold = replaced_byte; - strcpy(kdb_buffer, cphold); - len = strlen(kdb_buffer); + len = strlen(cphold); + /* Use memmove() because the buffers overlap */ + memmove(kdb_buffer, cphold, len + 1); next_avail = kdb_buffer + len; size_avail = sizeof(kdb_buffer) - len; } -- 2.50.1
