libsframe asan: avoid generating misaligned loads
There are two places where unaligned loads were seen on aarch64: - #1. access to the SFrame FRE stack offsets in the in-memory representation/abstraction provided by libsframe. - #2. access to the SFrame FRE start address in the on-disk representation of the frame row entry. For #1, we can fix this by reordering the struct members of sframe_frame_row_entry in libsframe/sframe-api.h. For #2, we need to default to using memcpy instead, and copy out the bytes to a location for output. SFrame format is an unaligned on-disk format. As such, there are other blobs of memory in the on-disk SFrame FRE that are on not on their natural boundaries. But that does not pose further problems yet, because the users are provided access to the on-disk SFrame FRE data via libsframe's sframe_frame_row_entry, the latter has its' struct members aligned on their respective natural boundaries (and initialized using memcpy). PR 29856 libsframe asan: load misaligned at sframe.c:516 ChangeLog: PR libsframe/29856 * bfd/elf64-x86-64.c: Adjust as the struct members have been reordered. * libsframe/sframe.c (sframe_decode_fre_start_address): Use memcpy to perform 16-bit/32-bit reads. * libsframe/testsuite/libsframe.encode/encode-1.c: Adjust as the struct members have been reordered. include/ChangeLog: PR libsframe/29856 * sframe-api.h: Reorder fre_offsets for natural alignment.
This commit is contained in:
Indu Bhagat
parent
69de431392
commit
8c078abdc2
4 changed files with 42 additions and 24 deletions
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@ -822,48 +822,48 @@ static const bfd_byte elf_x86_64_eh_frame_non_lazy_plt[] =
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static const sframe_frame_row_entry elf_x86_64_sframe_null_fre =
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{
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0,
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B), /* FRE info. */
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{16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} /* 12 bytes. */
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{16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, /* 12 bytes. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
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};
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/* .sframe FRE covering the .plt section entry. */
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static const sframe_frame_row_entry elf_x86_64_sframe_plt0_fre1 =
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{
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0, /* SFrame FRE start address. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B), /* FRE info. */
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{16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} /* 12 bytes. */
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{16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, /* 12 bytes. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
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};
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/* .sframe FRE covering the .plt section entry. */
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static const sframe_frame_row_entry elf_x86_64_sframe_plt0_fre2 =
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{
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6, /* SFrame FRE start address. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B), /* FRE info. */
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{24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} /* 12 bytes. */
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{24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, /* 12 bytes. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
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};
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/* .sframe FRE covering the .plt section entry. */
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static const sframe_frame_row_entry elf_x86_64_sframe_pltn_fre1 =
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{
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0, /* SFrame FRE start address. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B), /* FRE info. */
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{8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} /* 12 bytes. */
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{8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, /* 12 bytes. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
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};
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/* .sframe FRE covering the .plt section entry. */
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static const sframe_frame_row_entry elf_x86_64_sframe_pltn_fre2 =
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{
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11, /* SFrame FRE start address. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B), /* FRE info. */
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{16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} /* 12 bytes. */
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{16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, /* 12 bytes. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
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};
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/* .sframe FRE covering the second .plt section entry. */
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static const sframe_frame_row_entry elf_x86_64_sframe_sec_pltn_fre1 =
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{
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0, /* SFrame FRE start address. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B), /* FRE info. */
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{8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} /* 12 bytes. */
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{8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, /* 12 bytes. */
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SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
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};
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/* SFrame helper object for non-lazy PLT. Also used for IBT enabled PLT. */
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@ -34,13 +34,17 @@ typedef struct sframe_encoder_ctx sframe_encoder_ctx;
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/* User interfacing SFrame Row Entry.
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An abstraction provided by libsframe so the consumer is decoupled from
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the binary format representation of the same. */
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the binary format representation of the same.
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The members are best ordered such that they are aligned at their natural
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boundaries. This helps avoid usage of undesirable misaligned memory
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accesses. See PR libsframe/29856. */
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typedef struct sframe_frame_row_entry
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{
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uint32_t fre_start_addr;
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unsigned char fre_info;
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unsigned char fre_offsets[MAX_OFFSET_BYTES];
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unsigned char fre_info;
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} sframe_frame_row_entry;
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#define SFRAME_ERR ((int) -1)
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@ -652,6 +652,11 @@ sframe_frame_row_entry_copy (sframe_frame_row_entry *dst, sframe_frame_row_entry
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return 0;
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}
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/* Decode the SFrame FRE start address offset value from FRE_BUF in on-disk
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binary format, given the FRE_TYPE. Updates the FRE_START_ADDR.
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Returns 0 on success, SFRAME_ERR otherwise. */
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static int
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sframe_decode_fre_start_address (const char *fre_buf,
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uint32_t *fre_start_addr,
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@ -659,6 +664,9 @@ sframe_decode_fre_start_address (const char *fre_buf,
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{
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uint32_t saddr = 0;
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int err = 0;
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size_t addr_size = 0;
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addr_size = sframe_fre_start_addr_size (fre_type);
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if (fre_type == SFRAME_FRE_TYPE_ADDR1)
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{
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@ -668,12 +676,18 @@ sframe_decode_fre_start_address (const char *fre_buf,
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else if (fre_type == SFRAME_FRE_TYPE_ADDR2)
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{
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uint16_t *ust = (uint16_t *)fre_buf;
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saddr = (uint32_t)*ust;
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/* SFrame is an unaligned on-disk format. Using memcpy helps avoid the
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use of undesirable unaligned loads. See PR libsframe/29856. */
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uint16_t tmp = 0;
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memcpy (&tmp, ust, addr_size);
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saddr = (uint32_t)tmp;
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}
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else if (fre_type == SFRAME_FRE_TYPE_ADDR4)
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{
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uint32_t *uit = (uint32_t *)fre_buf;
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saddr = (uint32_t)*uit;
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int32_t tmp = 0;
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memcpy (&tmp, uit, addr_size);
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saddr = (uint32_t)tmp;
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}
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else
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return sframe_set_errno (&err, SFRAME_ERR_INVAL);
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@ -33,10 +33,10 @@ add_fde1 (sframe_encoder_ctx *encode, int idx)
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int i, err;
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/* A contiguous block containing 4 FREs. */
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sframe_frame_row_entry fres[]
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= { {0x0, 0x3, {0x8, 0, 0}},
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{0x1, 0x5, {0x10, 0xf0, 0}},
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{0x4, 0x4, {0x10, 0xf0, 0}},
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{0x1a, 0x5, {0x8, 0xf0, 0}}
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= { {0x0, {0x8, 0, 0}, 0x3},
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{0x1, {0x10, 0xf0, 0}, 0x5},
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{0x4, {0x10, 0xf0, 0}, 0x4},
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{0x1a, {0x8, 0xf0, 0}, 0x5}
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};
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unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
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@ -58,10 +58,10 @@ add_fde2 (sframe_encoder_ctx *encode, int idx)
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int i, err;
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/* A contiguous block containing 4 FREs. */
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sframe_frame_row_entry fres[]
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= { {0x0, 0x3, {0x8, 0, 0}},
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{0x1, 0x5, {0x10, 0xf0, 0}},
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{0x4, 0x4, {0x10, 0xf0, 0}},
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{0xf, 0x5, {0x8, 0xf0, 0}}
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= { {0x0, {0x8, 0, 0}, 0x3},
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{0x1, {0x10, 0xf0, 0}, 0x5},
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{0x4, {0x10, 0xf0, 0}, 0x4},
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{0xf, {0x8, 0xf0, 0}, 0x5}
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};
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unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
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