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altera-stapl: altera_get_note: prevent write beyond end of 'key' 

altera_get_note is called from altera_init, where key is kzalloc(33).

When the allocation functions are annotated to allow the compiler to see
the sizes of objects, and with FORTIFY_SOURCE, we see:

In file included from drivers/misc/altera-stapl/altera.c:14:0:
In function ‘strlcpy’,
    inlined from ‘altera_init’ at drivers/misc/altera-stapl/altera.c:2189:5:
include/linux/string.h:378:4: error: call to ‘__write_overflow’ declared with attribute error: detected write beyond size of object passed as 1st parameter
    __write_overflow();
    ^~~~~~~~~~~~~~~~~~

That refers to this code in altera_get_note:

    if (key != NULL)
            strlcpy(key, &p[note_strings +
                            get_unaligned_be32(
                            &p[note_table + (8 * i)])],
                    length);

The error triggers because the length of 'key' is 33, but the copy
uses length supplied as the 'length' parameter, which is always
256. Split the size parameter into key_len and val_len, and use the
appropriate length depending on what is being copied.

Detected by compiler error, only compile-tested.

Cc: "Igor M. Liplianin" <liplianin@netup.ru>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Link: https://lore.kernel.org/r/20200120074344.504-2-dja@axtens.net
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/202002251042.D898E67AC@keescook
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Daniel Axtens 2020-02-25 10:44:27 -08:00 committed by Greg Kroah-Hartman
parent 2669b8b0c7
commit 3745488e9d
1 changed files with 6 additions and 6 deletions
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12
drivers/misc/altera-stapl/altera.c
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@ -2112,8 +2112,8 @@ exit_done:
return status;
}
static int altera_get_note(u8 *p, s32 program_size,
s32 *offset, char *key, char *value, int length)
static int altera_get_note(u8 *p, s32 program_size, s32 *offset,
char *key, char *value, int keylen, int vallen)
/*
* Gets key and value of NOTE fields in the JBC file.
* Can be called in two modes: if offset pointer is NULL,
@ -2170,7 +2170,7 @@ static int altera_get_note(u8 *p, s32 program_size,
&p[note_table + (8 * i) + 4])];
if (value != NULL)
strlcpy(value, value_ptr, length);
strlcpy(value, value_ptr, vallen);
}
}
@ -2189,13 +2189,13 @@ static int altera_get_note(u8 *p, s32 program_size,
strlcpy(key, &p[note_strings +
get_unaligned_be32(
&p[note_table + (8 * i)])],
length);
keylen);
if (value != NULL)
strlcpy(value, &p[note_strings +
get_unaligned_be32(
&p[note_table + (8 * i) + 4])],
length);
vallen);
*offset = i + 1;
}
@ -2449,7 +2449,7 @@ int altera_init(struct altera_config *config, const struct firmware *fw)
__func__, (format_version == 2) ? "Jam STAPL" :
"pre-standardized Jam 1.1");
while (altera_get_note((u8 *)fw->data, fw->size,
&offset, key, value, 256) == 0)
&offset, key, value, 32, 256) == 0)
printk(KERN_INFO "%s: NOTE \"%s\" = \"%s\"\n",
__func__, key, value);
}