diff options
| -rw-r--r-- | Documentation/core-api/printk-formats.rst | 7 | ||||
| -rw-r--r-- | lib/test_printf.c | 22 | ||||
| -rw-r--r-- | lib/vsprintf.c | 136 |
3 files changed, 129 insertions, 36 deletions
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst index c37ec7cd9c06..b2cac8d76b66 100644 --- a/Documentation/core-api/printk-formats.rst +++ b/Documentation/core-api/printk-formats.rst @@ -58,6 +58,13 @@ A raw pointer value may be printed with %p which will hash the address before printing. The kernel also supports extended specifiers for printing pointers of different types. +Some of the extended specifiers print the data on the given address instead +of printing the address itself. In this case, the following error messages +might be printed instead of the unreachable information:: + + (null) data on plain NULL address + (efault) data on invalid address + Plain Pointers -------------- diff --git a/lib/test_printf.c b/lib/test_printf.c index 250ee864b8b8..359ae4fb1ece 100644 --- a/lib/test_printf.c +++ b/lib/test_printf.c @@ -239,6 +239,7 @@ plain_format(void) #define PTR ((void *)0x456789ab) #define PTR_STR "456789ab" #define PTR_VAL_NO_CRNG "(ptrval)" +#define ZEROS "" static int __init plain_format(void) @@ -268,7 +269,6 @@ plain_hash_to_buffer(const void *p, char *buf, size_t len) return 0; } - static int __init plain_hash(void) { @@ -326,6 +326,24 @@ test_hashed(const char *fmt, const void *p) } static void __init +null_pointer(void) +{ + test_hashed("%p", NULL); + test(ZEROS "00000000", "%px", NULL); + test("(null)", "%pE", NULL); +} + +#define PTR_INVALID ((void *)0x000000ab) + +static void __init +invalid_pointer(void) +{ + test_hashed("%p", PTR_INVALID); + test(ZEROS "000000ab", "%px", PTR_INVALID); + test("(efault)", "%pE", PTR_INVALID); +} + +static void __init symbol_ptr(void) { } @@ -571,6 +589,8 @@ static void __init test_pointer(void) { plain(); + null_pointer(); + invalid_pointer(); symbol_ptr(); kernel_ptr(); struct_resource(); diff --git a/lib/vsprintf.c b/lib/vsprintf.c index f471a658422f..b989f1e8f35b 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -612,12 +612,45 @@ static char *string_nocheck(char *buf, char *end, const char *s, return widen_string(buf, len, end, spec); } +/* + * This is not a fool-proof test. 99% of the time that this will fault is + * due to a bad pointer, not one that crosses into bad memory. Just test + * the address to make sure it doesn't fault due to a poorly added printk + * during debugging. + */ +static const char *check_pointer_msg(const void *ptr) +{ + char byte; + + if (!ptr) + return "(null)"; + + if (probe_kernel_address(ptr, byte)) + return "(efault)"; + + return NULL; +} + +static int check_pointer(char **buf, char *end, const void *ptr, + struct printf_spec spec) +{ + const char *err_msg; + + err_msg = check_pointer_msg(ptr); + if (err_msg) { + *buf = string_nocheck(*buf, end, err_msg, spec); + return -EFAULT; + } + + return 0; +} + static noinline_for_stack char *string(char *buf, char *end, const char *s, struct printf_spec spec) { - if ((unsigned long)s < PAGE_SIZE) - s = "(null)"; + if (check_pointer(&buf, end, s, spec)) + return buf; return string_nocheck(buf, end, s, spec); } @@ -792,6 +825,11 @@ char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_sp rcu_read_lock(); for (i = 0; i < depth; i++, d = p) { + if (check_pointer(&buf, end, d, spec)) { + rcu_read_unlock(); + return buf; + } + p = READ_ONCE(d->d_parent); array[i] = READ_ONCE(d->d_name.name); if (p == d) { @@ -822,8 +860,12 @@ static noinline_for_stack char *bdev_name(char *buf, char *end, struct block_device *bdev, struct printf_spec spec, const char *fmt) { - struct gendisk *hd = bdev->bd_disk; - + struct gendisk *hd; + + if (check_pointer(&buf, end, bdev, spec)) + return buf; + + hd = bdev->bd_disk; buf = string(buf, end, hd->disk_name, spec); if (bdev->bd_part->partno) { if (isdigit(hd->disk_name[strlen(hd->disk_name)-1])) { @@ -942,6 +984,9 @@ char *resource_string(char *buf, char *end, struct resource *res, int decode = (fmt[0] == 'R') ? 1 : 0; const struct printf_spec *specp; + if (check_pointer(&buf, end, res, spec)) + return buf; + *p++ = '['; if (res->flags & IORESOURCE_IO) { p = string_nocheck(p, pend, "io ", str_spec); @@ -1004,9 +1049,8 @@ char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec, /* nothing to print */ return buf; - if (ZERO_OR_NULL_PTR(addr)) - /* NULL pointer */ - return string(buf, end, NULL, spec); + if (check_pointer(&buf, end, addr, spec)) + return buf; switch (fmt[1]) { case 'C': @@ -1053,6 +1097,9 @@ char *bitmap_string(char *buf, char *end, unsigned long *bitmap, int i, chunksz; bool first = true; + if (check_pointer(&buf, end, bitmap, spec)) + return buf; + /* reused to print numbers */ spec = (struct printf_spec){ .flags = SMALL | ZEROPAD, .base = 16 }; @@ -1094,6 +1141,9 @@ char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap, int cur, rbot, rtop; bool first = true; + if (check_pointer(&buf, end, bitmap, spec)) + return buf; + rbot = cur = find_first_bit(bitmap, nr_bits); while (cur < nr_bits) { rtop = cur; @@ -1132,6 +1182,9 @@ char *mac_address_string(char *buf, char *end, u8 *addr, char separator; bool reversed = false; + if (check_pointer(&buf, end, addr, spec)) + return buf; + switch (fmt[1]) { case 'F': separator = '-'; @@ -1437,6 +1490,9 @@ char *ip_addr_string(char *buf, char *end, const void *ptr, { char *err_fmt_msg; + if (check_pointer(&buf, end, ptr, spec)) + return buf; + switch (fmt[1]) { case '6': return ip6_addr_string(buf, end, ptr, spec, fmt); @@ -1475,9 +1531,8 @@ char *escaped_string(char *buf, char *end, u8 *addr, struct printf_spec spec, if (spec.field_width == 0) return buf; /* nothing to print */ - if (ZERO_OR_NULL_PTR(addr)) - return string(buf, end, NULL, spec); /* NULL pointer */ - + if (check_pointer(&buf, end, addr, spec)) + return buf; do { switch (fmt[count++]) { @@ -1523,10 +1578,14 @@ char *escaped_string(char *buf, char *end, u8 *addr, struct printf_spec spec, return buf; } -static char *va_format(char *buf, char *end, struct va_format *va_fmt) +static char *va_format(char *buf, char *end, struct va_format *va_fmt, + struct printf_spec spec, const char *fmt) { va_list va; + if (check_pointer(&buf, end, va_fmt, spec)) + return buf; + va_copy(va, *va_fmt->va); buf += vsnprintf(buf, end > buf ? end - buf : 0, va_fmt->fmt, va); va_end(va); @@ -1544,6 +1603,9 @@ char *uuid_string(char *buf, char *end, const u8 *addr, const u8 *index = uuid_index; bool uc = false; + if (check_pointer(&buf, end, addr, spec)) + return buf; + switch (*(++fmt)) { case 'L': uc = true; /* fall-through */ @@ -1582,6 +1644,9 @@ char *netdev_bits(char *buf, char *end, const void *addr, unsigned long long num; int size; + if (check_pointer(&buf, end, addr, spec)) + return buf; + switch (fmt[1]) { case 'F': num = *(const netdev_features_t *)addr; @@ -1595,11 +1660,15 @@ char *netdev_bits(char *buf, char *end, const void *addr, } static noinline_for_stack -char *address_val(char *buf, char *end, const void *addr, const char *fmt) +char *address_val(char *buf, char *end, const void *addr, + struct printf_spec spec, const char *fmt) { unsigned long long num; int size; + if (check_pointer(&buf, end, addr, spec)) + return buf; + switch (fmt[1]) { case 'd': num = *(const dma_addr_t *)addr; @@ -1651,12 +1720,16 @@ char *time_str(char *buf, char *end, const struct rtc_time *tm, bool r) } static noinline_for_stack -char *rtc_str(char *buf, char *end, const struct rtc_time *tm, const char *fmt) +char *rtc_str(char *buf, char *end, const struct rtc_time *tm, + struct printf_spec spec, const char *fmt) { bool have_t = true, have_d = true; bool raw = false; int count = 2; + if (check_pointer(&buf, end, tm, spec)) + return buf; + switch (fmt[count]) { case 'd': have_t = false; @@ -1690,7 +1763,7 @@ char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec, { switch (fmt[1]) { case 'R': - return rtc_str(buf, end, (const struct rtc_time *)ptr, fmt); + return rtc_str(buf, end, (const struct rtc_time *)ptr, spec, fmt); default: return string_nocheck(buf, end, "(%ptR?)", spec); } @@ -1703,8 +1776,8 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec, if (!IS_ENABLED(CONFIG_HAVE_CLK)) return string_nocheck(buf, end, "(%pC?)", spec); - if (!clk) - return string(buf, end, NULL, spec); + if (check_pointer(&buf, end, clk, spec)) + return buf; switch (fmt[1]) { case 'n': @@ -1751,6 +1824,9 @@ char *flags_string(char *buf, char *end, void *flags_ptr, unsigned long flags; const struct trace_print_flags *names; + if (check_pointer(&buf, end, flags_ptr, spec)) + return buf; + switch (fmt[1]) { case 'p': flags = *(unsigned long *)flags_ptr; @@ -1825,8 +1901,8 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, if (!IS_ENABLED(CONFIG_OF)) return string_nocheck(buf, end, "(%pOF?)", spec); - if ((unsigned long)dn < PAGE_SIZE) - return string_nocheck(buf, end, "(null)", spec); + if (check_pointer(&buf, end, dn, spec)) + return buf; /* simple case without anything any more format specifiers */ fmt++; @@ -2021,18 +2097,6 @@ static noinline_for_stack char *pointer(const char *fmt, char *buf, char *end, void *ptr, struct printf_spec spec) { - const int default_width = 2 * sizeof(void *); - - if (!ptr && *fmt != 'K' && *fmt != 'x') { - /* - * Print (null) with the same width as a pointer so it makes - * tabular output look nice. - */ - if (spec.field_width == -1) - spec.field_width = default_width; - return string_nocheck(buf, end, "(null)", spec); - } - switch (*fmt) { case 'F': case 'f': @@ -2074,13 +2138,13 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, case 'U': return uuid_string(buf, end, ptr, spec, fmt); case 'V': - return va_format(buf, end, ptr); + return va_format(buf, end, ptr, spec, fmt); case 'K': return restricted_pointer(buf, end, ptr, spec); case 'N': return netdev_bits(buf, end, ptr, spec, fmt); case 'a': - return address_val(buf, end, ptr, fmt); + return address_val(buf, end, ptr, spec, fmt); case 'd': return dentry_name(buf, end, ptr, spec, fmt); case 't': @@ -2714,11 +2778,13 @@ int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args) case FORMAT_TYPE_STR: { const char *save_str = va_arg(args, char *); + const char *err_msg; size_t len; - if ((unsigned long)save_str > (unsigned long)-PAGE_SIZE - || (unsigned long)save_str < PAGE_SIZE) - save_str = "(null)"; + err_msg = check_pointer_msg(save_str); + if (err_msg) + save_str = err_msg; + len = strlen(save_str) + 1; if (str + len < end) memcpy(str, save_str, len); |