gsd-2024-26706
Vulnerability from gsd
Modified
2024-02-20 06:02
Details
In the Linux kernel, the following vulnerability has been resolved:
parisc: Fix random data corruption from exception handler
The current exception handler implementation, which assists when accessing
user space memory, may exhibit random data corruption if the compiler decides
to use a different register than the specified register %r29 (defined in
ASM_EXCEPTIONTABLE_REG) for the error code. If the compiler choose another
register, the fault handler will nevertheless store -EFAULT into %r29 and thus
trash whatever this register is used for.
Looking at the assembly I found that this happens sometimes in emulate_ldd().
To solve the issue, the easiest solution would be if it somehow is
possible to tell the fault handler which register is used to hold the error
code. Using %0 or %1 in the inline assembly is not posssible as it will show
up as e.g. %r29 (with the "%r" prefix), which the GNU assembler can not
convert to an integer.
This patch takes another, better and more flexible approach:
We extend the __ex_table (which is out of the execution path) by one 32-word.
In this word we tell the compiler to insert the assembler instruction
"or %r0,%r0,%reg", where %reg references the register which the compiler
choosed for the error return code.
In case of an access failure, the fault handler finds the __ex_table entry and
can examine the opcode. The used register is encoded in the lowest 5 bits, and
the fault handler can then store -EFAULT into this register.
Since we extend the __ex_table to 3 words we can't use the BUILDTIME_TABLE_SORT
config option any longer.
Aliases
{
"gsd": {
"metadata": {
"exploitCode": "unknown",
"remediation": "unknown",
"reportConfidence": "confirmed",
"type": "vulnerability"
},
"osvSchema": {
"aliases": [
"CVE-2024-26706"
],
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nparisc: Fix random data corruption from exception handler\n\nThe current exception handler implementation, which assists when accessing\nuser space memory, may exhibit random data corruption if the compiler decides\nto use a different register than the specified register %r29 (defined in\nASM_EXCEPTIONTABLE_REG) for the error code. If the compiler choose another\nregister, the fault handler will nevertheless store -EFAULT into %r29 and thus\ntrash whatever this register is used for.\nLooking at the assembly I found that this happens sometimes in emulate_ldd().\n\nTo solve the issue, the easiest solution would be if it somehow is\npossible to tell the fault handler which register is used to hold the error\ncode. Using %0 or %1 in the inline assembly is not posssible as it will show\nup as e.g. %r29 (with the \"%r\" prefix), which the GNU assembler can not\nconvert to an integer.\n\nThis patch takes another, better and more flexible approach:\nWe extend the __ex_table (which is out of the execution path) by one 32-word.\nIn this word we tell the compiler to insert the assembler instruction\n\"or %r0,%r0,%reg\", where %reg references the register which the compiler\nchoosed for the error return code.\nIn case of an access failure, the fault handler finds the __ex_table entry and\ncan examine the opcode. The used register is encoded in the lowest 5 bits, and\nthe fault handler can then store -EFAULT into this register.\n\nSince we extend the __ex_table to 3 words we can\u0027t use the BUILDTIME_TABLE_SORT\nconfig option any longer.",
"id": "GSD-2024-26706",
"modified": "2024-02-20T06:02:29.132735Z",
"schema_version": "1.4.0"
}
},
"namespaces": {
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"CVE_data_meta": {
"ASSIGNER": "cve@kernel.org",
"ID": "CVE-2024-26706",
"STATE": "PUBLIC"
},
"affects": {
"vendor": {
"vendor_data": [
{
"product": {
"product_data": [
{
"product_name": "Linux",
"version": {
"version_data": [
{
"version_affected": "\u003c",
"version_name": "1da177e4c3f4",
"version_value": "23027309b099"
},
{
"version_value": "not down converted",
"x_cve_json_5_version_data": {
"defaultStatus": "affected",
"versions": [
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.79",
"versionType": "custom"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.18",
"versionType": "custom"
},
{
"lessThanOrEqual": "6.7.*",
"status": "unaffected",
"version": "6.7.6",
"versionType": "custom"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.8",
"versionType": "original_commit_for_fix"
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]
}
}
]
}
}
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},
"vendor_name": "Linux"
}
]
}
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"data_format": "MITRE",
"data_type": "CVE",
"data_version": "4.0",
"description": {
"description_data": [
{
"lang": "eng",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nparisc: Fix random data corruption from exception handler\n\nThe current exception handler implementation, which assists when accessing\nuser space memory, may exhibit random data corruption if the compiler decides\nto use a different register than the specified register %r29 (defined in\nASM_EXCEPTIONTABLE_REG) for the error code. If the compiler choose another\nregister, the fault handler will nevertheless store -EFAULT into %r29 and thus\ntrash whatever this register is used for.\nLooking at the assembly I found that this happens sometimes in emulate_ldd().\n\nTo solve the issue, the easiest solution would be if it somehow is\npossible to tell the fault handler which register is used to hold the error\ncode. Using %0 or %1 in the inline assembly is not posssible as it will show\nup as e.g. %r29 (with the \"%r\" prefix), which the GNU assembler can not\nconvert to an integer.\n\nThis patch takes another, better and more flexible approach:\nWe extend the __ex_table (which is out of the execution path) by one 32-word.\nIn this word we tell the compiler to insert the assembler instruction\n\"or %r0,%r0,%reg\", where %reg references the register which the compiler\nchoosed for the error return code.\nIn case of an access failure, the fault handler finds the __ex_table entry and\ncan examine the opcode. The used register is encoded in the lowest 5 bits, and\nthe fault handler can then store -EFAULT into this register.\n\nSince we extend the __ex_table to 3 words we can\u0027t use the BUILDTIME_TABLE_SORT\nconfig option any longer."
}
]
},
"generator": {
"engine": "bippy-d3b290d2becc"
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"problemtype": {
"problemtype_data": [
{
"description": [
{
"lang": "eng",
"value": "n/a"
}
]
}
]
},
"references": {
"reference_data": [
{
"name": "https://git.kernel.org/stable/c/23027309b099ffc4efca5477009a11dccbdae592",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/23027309b099ffc4efca5477009a11dccbdae592"
},
{
"name": "https://git.kernel.org/stable/c/fa69a8063f8b27f3c7434a0d4f464a76a62f24d2",
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"url": "https://git.kernel.org/stable/c/fa69a8063f8b27f3c7434a0d4f464a76a62f24d2"
},
{
"name": "https://git.kernel.org/stable/c/ce31d79aa1f13a2345791f84935281a2c194e003",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/ce31d79aa1f13a2345791f84935281a2c194e003"
},
{
"name": "https://git.kernel.org/stable/c/8b1d72395635af45410b66cc4c4ab37a12c4a831",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/8b1d72395635af45410b66cc4c4ab37a12c4a831"
}
]
}
},
"nvd.nist.gov": {
"cve": {
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nparisc: Fix random data corruption from exception handler\n\nThe current exception handler implementation, which assists when accessing\nuser space memory, may exhibit random data corruption if the compiler decides\nto use a different register than the specified register %r29 (defined in\nASM_EXCEPTIONTABLE_REG) for the error code. If the compiler choose another\nregister, the fault handler will nevertheless store -EFAULT into %r29 and thus\ntrash whatever this register is used for.\nLooking at the assembly I found that this happens sometimes in emulate_ldd().\n\nTo solve the issue, the easiest solution would be if it somehow is\npossible to tell the fault handler which register is used to hold the error\ncode. Using %0 or %1 in the inline assembly is not posssible as it will show\nup as e.g. %r29 (with the \"%r\" prefix), which the GNU assembler can not\nconvert to an integer.\n\nThis patch takes another, better and more flexible approach:\nWe extend the __ex_table (which is out of the execution path) by one 32-word.\nIn this word we tell the compiler to insert the assembler instruction\n\"or %r0,%r0,%reg\", where %reg references the register which the compiler\nchoosed for the error return code.\nIn case of an access failure, the fault handler finds the __ex_table entry and\ncan examine the opcode. The used register is encoded in the lowest 5 bits, and\nthe fault handler can then store -EFAULT into this register.\n\nSince we extend the __ex_table to 3 words we can\u0027t use the BUILDTIME_TABLE_SORT\nconfig option any longer."
}
],
"id": "CVE-2024-26706",
"lastModified": "2024-04-03T17:24:18.150",
"metrics": {},
"published": "2024-04-03T15:15:53.293",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/23027309b099ffc4efca5477009a11dccbdae592"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8b1d72395635af45410b66cc4c4ab37a12c4a831"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ce31d79aa1f13a2345791f84935281a2c194e003"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/fa69a8063f8b27f3c7434a0d4f464a76a62f24d2"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
}
}
}
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