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efi/libstub: Use snprintf with %ls to convert the command line

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Now we can use snprintf to do the UTF-16 to UTF-8 translation for the
command line.

Drop the special "zero" trick to handle an empty command line. This was
unnecessary even before this since with options_chars == 0,
efi_utf16_to_utf8 would not have accessed options at all. snprintf won't
access it either with a precision of 0.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200518190716.751506-25-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Arvind Sankar
2020-05-18 15:07:16 -04:00
committed by Ard Biesheuvel
parent 15c316bcbc
commit 04b24409b4
1 changed files with 6 additions and 60 deletions
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66
drivers/firmware/efi/libstub/efi-stub-helper.c
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@@ -205,46 +205,6 @@ efi_status_t efi_parse_options(char const *cmdline)
return EFI_SUCCESS; return EFI_SUCCESS;
} }
/*
* Convert an UTF-16 string, not necessarily null terminated, to UTF-8.
*/
static u8 *efi_utf16_to_utf8(u8 *dst, const u16 *src, int n)
{
unsigned int c;
while (n--) {
c = *src++;
if (n && c >= 0xd800 && c <= 0xdbff &&
*src >= 0xdc00 && *src <= 0xdfff) {
c = 0x10000 + ((c & 0x3ff) << 10) + (*src & 0x3ff);
src++;
n--;
}
if (c >= 0xd800 && c <= 0xdfff)
c = 0xfffd; /* Unmatched surrogate */
if (c < 0x80) {
*dst++ = c;
continue;
}
if (c < 0x800) {
*dst++ = 0xc0 + (c >> 6);
goto t1;
}
if (c < 0x10000) {
*dst++ = 0xe0 + (c >> 12);
goto t2;
}
*dst++ = 0xf0 + (c >> 18);
*dst++ = 0x80 + ((c >> 12) & 0x3f);
t2:
*dst++ = 0x80 + ((c >> 6) & 0x3f);
t1:
*dst++ = 0x80 + (c & 0x3f);
}
return dst;
}
/* /*
* Convert the unicode UEFI command line to ASCII to pass to kernel. * Convert the unicode UEFI command line to ASCII to pass to kernel.
* Size of memory allocated return in *cmd_line_len. * Size of memory allocated return in *cmd_line_len.
@@ -254,18 +214,15 @@ char *efi_convert_cmdline(efi_loaded_image_t *image,
int *cmd_line_len, unsigned long max_addr) int *cmd_line_len, unsigned long max_addr)
{ {
const u16 *s2; const u16 *s2;
u8 *s1 = NULL;
unsigned long cmdline_addr = 0; unsigned long cmdline_addr = 0;
int load_options_chars = efi_table_attr(image, load_options_size) / 2; int options_chars = efi_table_attr(image, load_options_size) / 2;
const u16 *options = efi_table_attr(image, load_options); const u16 *options = efi_table_attr(image, load_options);
int options_bytes = 0; /* UTF-8 bytes */ int options_bytes = 0; /* UTF-8 bytes */
int options_chars = 0; /* UTF-16 chars */
efi_status_t status; efi_status_t status;
u16 zero = 0;
if (options) { if (options) {
s2 = options; s2 = options;
while (options_chars < load_options_chars) { while (options_chars--) {
u16 c = *s2++; u16 c = *s2++;
if (c == L'\0' || c == L'\n') if (c == L'\0' || c == L'\n')
@@ -276,7 +233,6 @@ char *efi_convert_cmdline(efi_loaded_image_t *image,
* The first part handles everything in the BMP. * The first part handles everything in the BMP.
*/ */
options_bytes += 1 + (c >= 0x80) + (c >= 0x800); options_bytes += 1 + (c >= 0x80) + (c >= 0x800);
options_chars++;
/* /*
* Add one more byte for valid surrogate pairs. Invalid * Add one more byte for valid surrogate pairs. Invalid
* surrogates will be replaced with 0xfffd and take up * surrogates will be replaced with 0xfffd and take up
@@ -288,35 +244,25 @@ char *efi_convert_cmdline(efi_loaded_image_t *image,
* we must ignore it since we can't access the * we must ignore it since we can't access the
* low surrogate. * low surrogate.
*/ */
if (options_chars == load_options_chars) { if (!options_chars) {
options_bytes -= 3; options_bytes -= 3;
options_chars--;
break;
} else if ((*s2 & 0xfc00) == 0xdc00) { } else if ((*s2 & 0xfc00) == 0xdc00) {
options_bytes++; options_bytes++;
options_chars++; options_chars--;
s2++; s2++;
} }
} }
} }
} }
if (!options_chars) {
/* No command line options, so return empty string*/
options = &zero;
}
options_bytes++; /* NUL termination */ options_bytes++; /* NUL termination */
status = efi_allocate_pages(options_bytes, &cmdline_addr, max_addr); status = efi_allocate_pages(options_bytes, &cmdline_addr, max_addr);
if (status != EFI_SUCCESS) if (status != EFI_SUCCESS)
return NULL; return NULL;
s1 = (u8 *)cmdline_addr; snprintf((char *)cmdline_addr, options_bytes, "%.*ls",
s2 = (const u16 *)options; options_bytes - 1, options);
s1 = efi_utf16_to_utf8(s1, s2, options_chars);
*s1 = '\0';
*cmd_line_len = options_bytes; *cmd_line_len = options_bytes;
return (char *)cmdline_addr; return (char *)cmdline_addr;