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authorIndu Bhagat <indu.bhagat@oracle.com>2023-01-06 09:29:48 -0800
committerIndu Bhagat <indu.bhagat@oracle.com>2023-01-06 09:29:48 -0800
commitcd9aea32cffd8089f6f63f4eb86d4dccfc0b3850 (patch)
treef37383b0a8e0bcafc059af016f7f9c2efa4be087 /libsframe
parent47bb5b33f742b4338bfa9608288830aecb085da4 (diff)
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libsframe: adjust an incorrect check in flip_sframe
When sframe_encoder_write needs to flip the buffer containing the SFrame section before writing, it is not necessary that the SFrame FDES are in the order of their sfde_func_start_fre_off. On the contrary, SFrame FDEs will be sorted in the order of their start address. So, remove this incorrect assumption which is basically assuming that the last sfde_func_start_fre_off seen will help determine the end of the flipped buffer. The function now keeps track of the bytes_flipped and then compares it with the expected value. Also, added two more checks at appropriate places: - check that the SFrame FDE read is within bounds - check that the SFrame FRE read is within bounds libsframe/ * sframe.c (flip_sframe): Adjust an incorrect check. Add other checks to ensure reads are within the buffer size.
Diffstat (limited to 'libsframe')
-rw-r--r--libsframe/sframe.c22
1 files changed, 13 insertions, 9 deletions
diff --git a/libsframe/sframe.c b/libsframe/sframe.c
index 4aada1a..d206780 100644
--- a/libsframe/sframe.c
+++ b/libsframe/sframe.c
@@ -401,7 +401,10 @@ flip_sframe (char *frame_buf, size_t buf_size, uint32_t to_foreign)
unsigned int fre_type = 0;
uint32_t fre_offset = 0;
size_t esz = 0;
+ size_t hdrsz = 0;
int err = 0;
+ /* For error checking. */
+ size_t bytes_flipped = 0;
/* Header must be in host endianness at this time. */
ihp = (sframe_header *)frame_buf;
@@ -411,14 +414,18 @@ flip_sframe (char *frame_buf, size_t buf_size, uint32_t to_foreign)
/* The contents of the SFrame header are safe to read. Get the number of
FDEs and the first FDE in the buffer. */
+ hdrsz = sframe_get_hdr_size (ihp);
num_fdes = ihp->sfh_num_fdes;
- fdes = frame_buf + sframe_get_hdr_size (ihp) + ihp->sfh_fdeoff;
+ fdes = frame_buf + hdrsz + ihp->sfh_fdeoff;
fdep = (sframe_func_desc_entry *)fdes;
j = 0;
prev_frep_index = 0;
for (i = 0; i < num_fdes; fdep++, i++)
{
+ if ((char*)fdep >= (frame_buf + buf_size))
+ goto bad;
+
if (to_foreign)
{
num_fres = fdep->sfde_func_num_fres;
@@ -427,6 +434,7 @@ flip_sframe (char *frame_buf, size_t buf_size, uint32_t to_foreign)
}
flip_fde (fdep);
+ bytes_flipped += sizeof (sframe_func_desc_entry);
if (!to_foreign)
{
@@ -441,20 +449,16 @@ flip_sframe (char *frame_buf, size_t buf_size, uint32_t to_foreign)
{
if (flip_fre (fp, fre_type, &esz))
goto bad;
+ bytes_flipped += esz;
- if (esz == 0)
+ if (esz == 0 || esz > buf_size)
goto bad;
fp += esz;
}
prev_frep_index = j;
}
- /* All FREs must have been endian flipped by now. */
- if (j != ihp->sfh_num_fres)
- goto bad;
- /* Contents, if any, must have been processed by now.
- Recall that .sframe section with just a SFrame header may be generated by
- GAS if no SFrame FDEs were found for the input file. */
- if (ihp->sfh_num_fres && ((frame_buf + buf_size) != (void*)fp))
+ /* All FDEs and FREs must have been endian flipped by now. */
+ if ((j != ihp->sfh_num_fres) || (bytes_flipped != (buf_size - hdrsz)))
goto bad;
/* Success. */